Asymptomatic hematuria in children: Korean Society of Pediatric Nephrology recommendations for diagnosis and management.

Hematuria is a relatively common condition among school-aged children. Because international guidelines for asymptomatic hematuria in children are unavailable, developing practical guidelines for the diagnosis and management of asymptomatic hematuria based on scientific evidence while considering real-world practice settings, values, and patient and physician preferences is essential. The Korean Society of Pediatric Nephrology developed clinical guidelines to address key questions regarding the diagnosis and management of asymptomatic hematuria in children.

Effects of hormone therapy on the clinical outcomes of endoscopic intervention in patients with endometriosis-related ureteral obstruction.

PURPOSE: We investigated whether endoscopic interventions, including laser endoureterotomy and balloon dilatation following hormone therapy, are a good choice to treat ureteral obstruction due to ureteral endometriosis instead of laparoscopic or open surgery. MATERIALS AND METHODS: Patients with ureteral obstruction due to endometriosis who underwent endoscopic intervention between 2004 and 2021 were reviewed. Patients with other causes of ureteral obstruction or previous ureteral surgery were excluded from the study. The primary endpoint was the 3-month success rate of endoscopic intervention with or without hormone therapy. Secondary endpoints were the success rate of endoscopic intervention between the hormone-treated and hormone-untreated groups at 6 months and the success rate according to the hormone therapy response of endometriosis at 3 and 6 months. RESULTS: Eighteen patients with 19 ureter units were evaluated in this study, including 12 patients receiving hormone therapy and six patients not receiving hormone therapy. Among patients receiving hormone therapy, one patient had bilateral ureteral obstruction. The success rate of endoscopic intervention was higher in patients who received hormone therapy than in those who did not receive hormone therapy three months after endoscopic intervention (76.9% vs. 0.0%, p=0.003). The same result was also found 6 months after endoscopic intervention (75.0% vs. 0.0%, p=0.005). In addition, the success rates were higher in the hormone-responsive group than in the non-responsive group (100.0% vs. 57.1%), although the difference was not statistically significant (p=0.122). CONCLUSIONS: Ureteral obstruction caused by endometriosis can be effectively treated by endoscopic intervention with hormone therapy in select patients.

Feasibility of a deep learning-based diagnostic platform to evaluate lower urinary tract disorders in men using simple uroflowmetry.

PURPOSE: To diagnose lower urinary tract symptoms (LUTS) in a noninvasive manner, we created a prediction model for bladder outlet obstruction (BOO) and detrusor underactivity (DUA) using simple uroflowmetry. In this study, we used deep learning to analyze simple uroflowmetry. MATERIALS AND METHODS: We performed a retrospective review of 4,835 male patients aged ≥40 years who underwent a urodynamic study at a single center. We excluded patients with a disease or a history of surgery that could affect LUTS. A total of 1,792 patients were included in the study. We extracted a simple uroflowmetry graph automatically using the ABBYY Flexicapture® image capture program (ABBYY, Moscow, Russia). We applied a convolutional neural network (CNN), a deep learning method to predict DUA and BOO. A 5-fold cross-validation average value of the area under the receiver operating characteristic (AUROC) curve was chosen as an evaluation metric. When it comes to binary classification, this metric provides a richer measure of classification performance. Additionally, we provided the corresponding average precision-recall (PR) curves. RESULTS: Among the 1,792 patients, 482 (26.90%) had BOO, and 893 (49.83%) had DUA. The average AUROC scores of DUA and BOO, which were measured using 5-fold cross-validation, were 73.30% (mean average precision [mAP]=0.70) and 72.23% (mAP=0.45), respectively. CONCLUSIONS: Our study suggests that it is possible to differentiate DUA from non-DUA and BOO from non-BOO using a simple uroflowmetry graph with a fine-tuned VGG16, which is a well-known CNN model.

Development and Validation of a Scoring System for Assessment of Clinical Failure after Pediatric Robot-Assisted Laparoscopic Extravesical Ureteral Reimplantation: A Multi-Center Study.

We aimed to develop and validate a scoring system as an objective assessment tool for predicting clinical failure after pediatric robotic extravesical ureteral reimplantation. Data for this multi-institutional retrospective cohort was obtained from two tertiary referral hospitals. We defined clinical failure as incomplete radiographic resolution or post-operative febrile UTI. Patients were stratified into low, intermediate, and high-risk groups according to the score. External validation was performed using the model projected to the external validation cohort. An amount of 115 renal units in the development cohort and 46 renal units in the validation cohort were analyzed. The prediction score was calculated with weighted points to each variable according to their regression coefficient as age (year) + BMI + BBD times 10 + VUR grade times 7 + console time (h) + hospital stay times 6. The C-index of our scoring system was 0.850 and 0.770 in the development and validation cohorts, respectively. Clinical failure was significantly different among risk groups: 0% (low-risk), 3.3% (intermediate-risk), and 22.2% (high-risk) (p = 0.004) in the development cohort. A novel scoring system using multiple pre- and intra-operative variables provides a prediction of children at risk of failure after robotic extravesical ureteral reimplantation.

Prediction of Recurrent Urinary Tract Infection in Paediatric Patients by Deep Learning Analysis of 99mTc-DMSA Renal Scan.

Purpose: Tc-99m dimercaptosuccinic acid (99mTc-DMSA) renal scan is an important tool for the assessment of childhood urinary tract infection (UTI), vesicoureteral reflux (VUR), and renal scarring. We evaluated whether a deep learning (DL) analysis of 99mTc-DMSA renal scans could predict the recurrence of UTI better than conventional clinical factors. Methods: the subjects were 180 paediatric patients diagnosed with UTI, who underwent immediate post-therapeutic 99mTc-DMSA renal scans. The primary outcome was the recurrence of UTI during the follow-up period. For the DL analysis, a convolutional neural network (CNN) model was used. Age, sex, the presence of VUR, the presence of cortical defects on the 99mTc-DMSA renal scan, split renal function (SRF), and DL prediction results were used as independent factors for predicting recurrent UTI. The diagnostic accuracy for predicting recurrent UTI was statistically compared between independent factors. Results: The sensitivity, specificity and accuracy for predicting recurrent UTI were 44.4%, 88.9%, and 82.2% by the presence of VUR; 44.4%, 76.5%, and 71.7% by the presence of cortical defect; 74.1%, 80.4%, and 79.4% by SRF (optimal cut-off = 45.93%); and 70.4%, 94.8%, and 91.1% by the DL prediction results. There were no significant differences in sensitivity between all independent factors (p > 0.05, for all). The specificity and accuracy of the DL prediction results were significantly higher than those of the other factors. Conclusion: DL analysis of 99mTc-DMSA renal scans may be useful for predicting recurrent UTI in paediatric patients. It is an efficient supportive tool to predict poor prognosis without visually demonstrable cortical defects in 99mTc-DMSA renal scans.

The Feasibility of Pop-Dusting Using High-Power Laser (2 J × 50 Hz) in Retrograde Intrarenal Surgery for Renal Stones: Retrospective Single-Center Experience.

Objective: Recently, retrograde intrarenal surgery (RIRS) using laser lithotripsy has become popular. However, the optimal laser energy setting for pop-dusting has not been established. In this study, we report our experiences of RIRS using the high-power (up to 100 W) pop-dusting (HPPD) technique. Methods: This study retrospectively assessed 82 cases with RIRS using HPPD. Patients who underwent abdominal CT or mercaptoacetyltriglycine (MAG3) diuretic renal scan at 3 months postoperatively were included in this study. Patient and stone characteristics and perioperative and postoperative outcomes were evaluated. Results: The average number of renal stones was 3.67 ± 4.11, and the average length of the largest stones was 13.30 ± 6.41 mm. The mean Hounsfield units was 959.99 ± 384.73. The operation time was 58.10 ± 26.67 minutes. The mean HPPD time was 11.93 ± 9.48 minutes, with settings of 1.97 ± 0.25 J and 48.78 ± 3.29 Hz. The stone-free rate was 89%. The mean hospital stay was 1.68 ± 1.29 days. Pelvicaliceal and ureter injuries were observed in 9.8% and 32.9% of the study population, respectively. However, there was no transfusion, subcapsular hematoma, persistent urinary leakage, ureteral or infundibular stricture, or renal functional deterioration. There was transient postoperative fever in 12.2% of the study population. Conclusions: HPPD could be performed safely during RIRS for renal stones without significant complications such as collecting system injury or bleeding. High-power laser mode (up to 100 W) can be a safe and effective choice for pop-dusting during RIRS, especially for large and hard stones.

Preoperative Bladder Bowel Dysfunction Is the Most Important Predictive Factor for Postoperative Urinary Retention After Robot-Assisted Laparoscopic Ureteral Reimplantation via An Extravesical Approach: A Multi-Center Study.

Introduction: Postoperative acute urinary retention (pAUR) is a known occurrence after robot-assisted laparoscopic ureteral reimplantation via an extravesical approach (RALUR-EV). We hypothesized that the risk factor of pAUR after RALUR-EV might be similar to that of pAUR after open reimplantation. We aimed at performing a retrospective multi-institutional study to evaluate the risk factors for pAUR after RALUR-EV. Materials and Methods: Perioperative data collected from two tertiary referral hospitals included demographics and perioperative variables such as bladder bowel dysfunction (BBD) status, vesicoureteral reflux (VUR) grade, and laterality. pAUR was defined as the need for urethral catheter replacement after removal of the initial postoperative catheter. Univariate and multivariate analyses were performed to identify risk factors for pAUR. Results: A total of 117 patients with 174 renal units from the 2 hospitals were enrolled in this study. The median age at the time of surgery was 5 (0.3-19) years. Bilateral RALUR-EV was performed in 57 (48.7%) cases. pAUR rate was 3.4% in all patients and 7.0% in 57 patients with bilateral VUR. All four cases of pAUR occurred after bilateral surgery. Univariate analysis showed age (p = 0.037), weight (p = 0.039), height (p = 0.040), and bilaterality (p = 0.037) as risk factors of pAUR. In a multivariate analysis, BBD was the only significant risk factor of pAUR (p = 0.037). Conclusion: Urinary retention after RALUR-EV occurred less frequently when compared with the previously reported open surgery series. pAUR was seen only in bilateral cases in our series. Preoperative history of BBD, but not male gender or length of surgical time, was the only risk factor of pAUR after RALUR-EV.

Pneumovesicoscopic bladder tumor resection in a young boy whose urethra was too small to use a resectoscope.

OBJECTIVE: To describe our experience with pneumovesicoscopic bladder tumor resection in a young boy whose urethra was too small to use a resectoscope. METHODS: An 11-year-old boy presented with gross hematuria. The patient was found to have a 2 cm-sized bladder tumor on ultrasound. The patient's urethra was too small to use a pediatric resectoscope, making it impossible to perform a transurethral resection of the bladder tumor. Therefore, pneumovesicoscopic bladder tumor resection was performed. En-bloc resection was performed successfully using 3 mm laparoscopic instruments, and the tumor was safely retrieved within an endo-bag made with a surgical glove. RESULTS: On postoperative day 1, the Foley catheter was removed and the patient was discharged. The pathology report described bladder papillary urothelial carcinoma, grade II/III without lamina propria invasion. The patient underwent follow-up with ultrasonography and urine cytology every three to six months. There was no recurrence for 21 months after surgery. CONCLUSION: This video demonstrates a pneumovesicoscopic approach for the treatment of bladder tumor in a young patient whose urethra was too small to use a resectoscope. Pneumovesicoscopic bladder tumor resection is technically feasible and safe.

Treatment of lower urinary tract dysfunction facilitates awakening and affects the cure rate in patients with nonmonosymptomatic enuresis.

PURPOSE: Poor awakening in patients with enuresis has been assumed to be an adaptation to the chronic influence of arousal stimuli like lower urinary tract dysfunction (LUTD). This study aimed to examine the effect of controlling LUTD on improvement of awakening and cure of enuresis. MATERIALS AND METHODS: Data for 119 enuretic patients with overactive bladder were retrospectively analyzed. The patients received urotherapy, laxatives, and anticholinergic agents. LUTD symptoms and enuresis were regularly monitored every 3 months. History of waking up because of bedwetting (ability to awaken, AA) was used as a surrogate marker of arousal and was graded at baseline and every 3 months of treatment. Changing distribution of each grade of AA was associated with other LUTD symptoms. Multivariate analysis was applied to understand whether the lack of improvement in AA might harbor any prognostic implications regarding cure of enuresis. RESULTS: Decreasing number of LUTD with treatment corresponded to increasing number of better AA. Enuresis was resolved completely in 88 patients in a median time of 7 months. Failure to show even single episode of awakening before bedwetting within 6 months of treatment and persistent daytime incontinence were identified as risk factors for treatment resistance until 18 months of treatment. CONCLUSIONS: Controlling LUTD symptoms in the management of nonmonosymptomatic enuresis was crucial for not only the treatment of enuresis but also for allowing the patients to obtain better arousal. AA tended to improve subsequent to bladder control and may contribute to the cure of enuresis.

Botryoid Wilms Tumor in a Neonate Presenting with Fetal Hydronephrosis: A Case Report.

Botryoid Wilms tumor, a very rare variant of Wilms tumor, arises from the pelvocalyceal system, and its occurrence in the fetal or neonatal period has never been reported in the literature. Herein, we report an exceedingly rare and challenging case of botryoid Wilms tumor in a neonate who initially presented with fetal hydronephrosis. Postnatal ultrasonography revealed multiple lobulating hypoechoic masses with varying degrees of intralesional vascularity within the dilated pelvocalyceal system. To our knowedge, this is a case report of botryoid Wilms tumor of the youngest child in English literature.

NiMoFe and NiMoFeP as Complementary Electrocatalysts for Efficient Overall Water Splitting and Their Application in PV-Electrolysis with STH 12.3.

Complementary water splitting electrocatalysts used simultaneously in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can simplify water splitting systems. Herein, earth-abundant NiMoFe (NMF) and phosphorized NiMoFeP (NMFP) are synthesized as complementary overall water splitting (OWS) catalysts. First, NMF is tested as both the HER and OER promoter, which exhibits low overpotentials of 68 (HER) and 337 mV (OER). A quaternary NMFP is then prepared by simple phosphorization of NMF, which shows a much lower OER overpotential of 286 mV. The enhanced OER activity is attributed to the unique surface/core structure of NMFP. The surface phosphate acts as a proton transport mediator and expedites the rate-determining step. With the application of OER potential, the NMFP surface is composed of Ni(OH)2 and FeOOH, active sites for OER, but the inner core consists of Ni, Mo, and Fe metals, serving as a conductive electron pathway. OWS with NMF-NMFP requires an applied voltage of 1.452 V to generate 10 mA cm-2 , which is one of the lowest values among OWS results with transition-metal-based electrocatalysts. Furthermore, the catalysts are combined with tandem perovskite solar cells for photovoltaic (PV)-electrolysis, producing a high solar-to-hydrogen (STH) conversion efficiency of 12.3%.

Does de novo hydronephrosis after pediatric robot-assisted laparoscopic ureteral re-implantation behave similarly to open re-implantation?

BACKGROUND: While open ureteral re-implantation surgery is the gold standard for surgical correction of vesicoureteral reflux (VUR), robot-assisted laparoscopic ureteral re-implantation via an extravesical approach (RALUR-EV) has become a minimally invasive alternative. Previous studies have shown that transient hydronephrosis after open re-implantation can occur in up to 28% of patients. However, previous studies have also shown that de novo hydronephrosis after open re-implantation is not predictive of final differential renal function. OBJECTIVE: A retrospective review was performed to characterize the natural history of postoperative hydronephrosis after RALUR-EV for primary VUR in pediatric patients. STUDY DESIGN: A retrospective chart review of a single-surgeon series was performed for pediatric patients who underwent RALUR-EV for primary VUR. The severity of de novo hydronephrosis was assessed using the Society for Fetal Urology (SFU) grading system via renal ultrasound at the 1-month postoperative follow-up. Renal ultrasound was performed at least every six months. Radiographic success was defined as complete resolution of VUR on the voiding cystourethrogram at the 4-month mark. Patient demographics, surgery duration, length of hospital stay, pre-operative and postoperative VUR grades, and follow-up time periods were collected. Patients with other associated urinary pathology and patients lost to follow-up were excluded from the study. RESULTS: A total of 87 patients (121 kidney units) with primary VUR who underwent RALUR-EV met the inclusion criteria. SFU grade 1-3 hydronephrosis was noted in 30.3% (36/119) of kidney units at the 1-month mark, but 83.9% (26/31) cases with hydronephrosis completely resolved in a median time of 7.9 months (range: 3.4-21.0 months), and all four cases with unresolved hydronephrosis were downgraded to SFU grade 1 without the need for intervention. DISCUSSION: A radiographic success rate of 96% was demonstrated in this cohort, which is comparable with that of historical open re-implantation series. A similar rate of de novo hydronephrosis was also noted in this cohort when compared with that of previous open re-implantation series, but de novo hydronephrosis after RALUR-EV had a similar or more rapid resolution rate than that previously reported after open intravesical and extravesical re-implantation series. CONCLUSION: De novo hydronephrosis after RALUR-EV behaves similarly to de novo hydronephrosis after open ureteral re-implantation, where de novo hydronephrosis is present in up to 30% of pediatric patients who underwent RALUR-EV. The hydronephrosis self-resolves without the need for intervention in the overwhelming majority of cases and resolves at a median time of 7.9 months after surgery.

Transvesicoscopic Politano-Leadbetter ureteral reimplantation in children with vesicoureteral reflux: A novel surgical technique.

Purpose: We introduce our novel procedure for transvesicoscopic ureteral reimplantation using the Politano-Leadbetter technique (TVUR-PL). We describe the detailed surgical procedure and report operative outcomes. Materials and Methods: We report a retrospective analysis of operative outcomes of TVUR-PL performed in children with vesicoureteral reflux (VUR) from January 2017 to July 2018. The analyzed operative outcomes included patient demographics, operative times, intra- and postoperative complications, indwelling duration of urethral Foley catheter, hospital length of stay, and treatment success. Results: A total of 47 patients (17 males, 30 females) underwent TVUR-PL during the study period, including 18 unilateral and 29 bilateral cases (76 ureters). All operations were successfully completed without open conversion. The median operative time was 121 minutes for unilateral cases and 178 minutes for bilateral cases. The median duration of placement of a urethral Foley catheter was 2 days. There were no intra- or postoperative complications. Only one patient (1/47 patients, 2.1%), who had no postoperative VUR on voiding cystourethrography, experienced febrile urinary tract infection during the follow-up period. Conclusions: Our novel TVUR-PL technique is a safe and effective minimally invasive surgical treatment option for children with VUR. The main advantage of our new operation is that it allows us to maintain the natural direction of the ureter after surgery.

Enhancing Durability and Photoelectrochemical Performance of the Earth Abundant Ni-Mo/TiO2 /CdS/CIGS Photocathode under Various pH Conditions.

Cu(In,Ga)(S,Se)2 (CIGS) is a promising photocathode material owing to its high absorption coefficient, adjustable band gap, and suitable band edge for the hydrogen evolution reaction (HER). However, most CIGS photocathodes have suffered from instability in applications that require a wide range of pH conditions and have utilized noble metal HER catalysts to achieve a high performance. Thus, improving the durability of the CIGS photocathode under various pH conditions and developing a cost-effective non-noble metal catalyst are critical issues in the photoelectrochemical (PEC) application of this promising photocathode material. Here, we catalyze the CIGS photocathode with Ni-Mo as a non-noble metal to enhance the PEC efficiency, and we employ atomically grown TiO2 to passivate the CdS/CIGS surface and improve the stability under a wide range of pH conditions. Our Ni-Mo alloy exhibits the best HER catalytic activity among reported earth-abundant HER catalysts in both acidic and alkaline solutions. The Ni-Mo/CdS/CIGS photocathode yields an onset potential of 0.5 V (vs. RHE) and a short-circuit photocurrent density as high as 15-25 mA cm-2 under various pH conditions ranging from 0.4 to 14, which is highly comparable to that of Pt/CdS/CIGS. Furthermore, the passivation of CdS/CIGS with a thin TiO2 layer, obtained by atomic layer deposition, effectively prevents the photocorrosion of CdS and the dissolution of the Mo back contact, which are the main causes of the degradation of the photocathode. The optimized Ni-Mo/TiO2 /CdS/CIGS photocathode produces a stable photocurrent density at 0 VRHE for 100 minutes except under strong alkaline conditions. The current work presents a very useful method to improve the efficiency and durability of the CIGS photocathodes with an earth-abundant metal catalyst, which completely replaces Pt.

Does the use of 5 mm instruments affect the outcomes of robot-assisted laparoscopic pyeloplasty in smaller working spaces? A comparative analysis of infants and older children.

INTRODUCTION: Pediatric robot-assisted laparoscopic (RAL) pyeloplasty has become a viable minimally invasive surgical option for ureteropelvic junction obstruction (UPJO) based on its efficacy and safety. However, RAL pyeloplasty in infants can be a challenging procedure because of the smaller working spaces. The use of the larger 8 mm instruments for these patients instead of the 5 mm instruments is common because of the shorter wrist lengths. OBJECTIVE: We hypothesized that the use of 5 mm instruments for RAL pyeloplasty in infants with smaller working spaces will have comparable perioperative parameters and surgical outcomes in comparison with older children with larger working spaces. STUDY DESIGN: We compared the perioperative parameters and surgical outcomes of RAL pyeloplasties performed by a single surgeon in infants and non-infant pediatric patients over a 2 year period. All of the procedures were performed using an 8.5 mm camera and 5 mm robotic instruments. Patient demographics, operative times, perioperative complications, hospital pain medication usage, hospital length of stay, and treatment success rates were compared between the two groups. RESULTS: A total of 65 pediatric RAL pyeloplasties were included in the study (16 infants and 49 non-infants, Table). There were no significant differences in gender, laterality, proportion of re-do pyeloplasty, or preoperative hydronephrosis grade between the two groups. All procedures were performed without conversion to open surgery or significant perioperative complications. There were no differences in segmental operative times (total operative time, console time, port placement time, time for dissection to UPJO, and anastomosis time), hospital pain medication usage, and hospital length of stay between the two groups (p > 0.05 for all comparisons). The treatment success rates were 93.8% (15/16) and 100% (49/49), respectively (p = 0.08). DISCUSSION: We present the first comparative study of infant and non-infant pediatric RAL pyeloplasty using 5 mm robotic instruments. An advantage of the current study is the use of a single surgeon's experience to compare RAL pyeloplasty outcomes in infants with those of older children, a group in which RAL pyeloplasty has already been shown to be efficacious and safe. Operative tips for infant RAL pyeloplasty are also provided. CONCLUSIONS: RAL pyeloplasty is a safe and effective surgical modality even in infants, with comparable perioperative parameters and outcomes as those in older children. The use of 5 mm instruments in infants does not affect outcomes and offers the potential for improved cosmesis.

Quantifying the Additional Difficulty of Pediatric Robot-Assisted Laparoscopic Re-Do Pyeloplasty: A Comparison of Primary and Re-Do Procedures.

BACKGROUND: Re-do pyeloplasty after failed open or laparoscopic ureteropelvic junction (UPJ) obstruction correction can be a challenging procedure because of scar formation at the previous anastomosis site and decreased vascularity of the ureter. This study compared the perioperative parameters for pediatric robot-assisted laparoscopic (RAL) primary and re-do pyeloplasties with an emphasis on the intra-operative parameters. MATERIALS AND METHODS: We compared the perioperative parameters of pediatric RAL procedures performed by a single surgeon at a tertiary care children's hospital for both primary ureteropelvic junction obstruction (UPJO) and recurrent UPJO after a previous open or laparoscopic procedure over 2013-2015. The operative time was subdivided as total operative time, console time, port placement time, dissection time to UPJ, and anastomosis time. RESULTS: A total of 65 pediatric RAL pyeloplasty procedures for UPJO were performed (55 primary and 10 re-do pyeloplasties) during the study period. The console times were 43.3% longer for re-do pyeloplasties than for primary pyeloplasties (133.0 ± 30.7 versus 92.8 ± 24.0 minutes, respectively, P < .01). The re-do cases had longer operative times, especially for UPJ exposure (52.2 ± 21.0 versus 28.0 ± 14.0 minutes, P < .01). There were no conversions to open surgery or significant perioperative complications. There was no difference in hospital pain medication usage and hospital length of stay between the 2 groups. The treatment success rates were 98.2% (54/55) and 100% (10/10), respectively. CONCLUSIONS: RAL re-do pyeloplasty is associated with significantly longer operative times as compared with primary pyeloplasties, especially during the exposure of the UPJ, but it is overall a safe and effective surgical modality for persistent/recurrent UPJO in children. As surgeons are increasingly asked for more accurate predictions of operative time lengths when scheduling cases, this information can be helpful for surgeons when scheduling these cases and with counseling families.

Multichannel Charge Transport of a BiVO4/(RGO/WO3)/W18O49 Three-Storey Anode for Greatly Enhanced Photoelectrochemical Efficiency.

Photoelectrochemical (PEC) solar conversion is a green strategy for addressing the energy crisis. In this study, a three-storey nanostructure BiVO4/(RGO/WO3)/W18O49 was fabricated as a PEC photoanode and demonstrated a highly enhanced PEC efficiency. The top and middle storeys are a reduced graphene oxide (RGO) layer and WO3 nanorods (NRs) decorated with BiVO4 nanoparticles (NPs), respectively. The bottom storey is the W18O49 film grown on a pure W substrate. In this novel design, experiments and modeling together demonstrated that the RGO layer and WO3 NRs with a fast carrier mobility can serve as multichannel pathways, sharing and facilitating electron transport from the BiVO4 NPs to the W18O49 film. The high conductivity of W18O49 can further enhance the charge transfer and retard electron-hole recombination, leading to a highly improved PEC efficiency of the BiVO4/WO3 heterojunction. As a result, the as-fabricated three-storey photoanode covered with FeOOH/NiOOH achieves an attractive PEC photocurrent density of 4.66 mA/cm2 at 1.5 V versus Ag/AgCl, which illustrates the promising potential of the three-storey hetero-nanostructure in future photoconversion applications.

Au-Coated Honeycomb Structure as an Efficient TCO-Free Counter-Electrode for Quantum-Dot-Sensitized Solar Cells.

This study reports the fabrication of a Petri dish patterned with cylindrical micro-cavities that are produced using a one-step solvent-immersion phase-separation process. The developed 3D honeycomb Petri dish is coated with a Au film through a sputtering method to be an efficient Au-coated FTO-free electrode for quantum-dot-sensitized solar cells. Due to the high specific active surface area of the electrode with the Au-coated honeycomb structure, the energy conversion efficiency of devices that use this electrode is 5.2 % compared to 4.4 and 4.7 % by devices using an Au-coated flat Petri dish and an Au-coated FTO electrode, respectively. This design strategy offers excellent potential for the fabrication of highly efficient counter electrodes with FTO-free substrates of flexible photovoltaic devices.

Environmentally benign synthesis of CuInS2/ZnO heteronanorods: visible light activated photocatalysis of organic pollutant/bacteria and study of its mechanism.

Due to its high light absorption coefficient and appropriate bandgap, CuInS2 (CIS) has been receiving much attention as an absorber material for thin film solar cells and also as a visible light photocatalyst. Herein we present heterostructured CIS/ZnO nanorods (NRs) in an attempt to enhance light absorption and facilitate charge separation/transfer in the photocatalysis system. CIS nanoparticles (NPs) were directly deposited on ZnO nanorod arrays (NRAs) to fabricate heterostructured CIS/ZnO NRAs using an environmentally benign, non-hydrazine solution reaction. These heterostructured NRAs are immobilized on FTO glass, which has additional merits of recyclability and bias-applicability. The ideal type-II band structure of CIS/ZnO enables efficient charge separation/transfer, which is confirmed by PL (photoluminescence) decay measurements. Also, the 1D-ZnO NR structure facilitates fast charge transfer along with enhancing light absorption via light scattering. These synergistic effects improved the photocatalytic activity in both organic dye and bacteria decomposition. The photodecomposition efficiency was further enhanced with an aid of external bias. The underlying photocatalytic mechanism was also investigated through controlled experiments under various scavenging conditions. The results suggest that reactive oxygen species (ROS) formed by multistep reduction of O2 play a main role in photocatalysis, while hole-induced photodecomposition is relatively deactivated due to the band structure of the heterostructures of CIS/ZnO.

Investigating the Unrevealed Photocatalytic Activity and Stability of Nanostructured Brookite TiO2 Film as an Environmental Photocatalyst.

Among three polymorphs of TiO2, the brookite is the least known phase in many aspects of its properties and photoactivities (especially comparable to anatase and rutile) because it is the rarest phase to be synthesized in the standard environment among the TiO2 polymorphs. In this study, we address the unrevealed photocatalytic properties of pure brookite TiO2 film as an environmental photocatalyst. Highly crystalline brookite nanostructures were synthesized on titanium foil using a well-designed hydrothermal reaction, without harmful precursors and selective etching of anatase, to afford pure brookite. The photocatalytic degradation of rhodamine B, tetramethylammonium chloride, and 4-chlorophenol on UV-illuminated pure brookite were investigated and compared with those on anatase and rutile TiO2. The present research explores the generation of OH radicals as main oxidants on brookite. In addition, tetramethylammonium, as a mobile OH radical indicator, was degraded over both pure anatase and brookite phases, but not rutile. The brookite phase showed much higher photoactivity among TiO2 polymorphs, despite its smaller surface area compared with anatase. This result can be ascribed to the following properties of the brookite TiO2 film: (i) the higher driving force with more negative flat-band potential, (ii) the efficient charge transfer kinetics with low resistance, and (iii) the generation of more hydroxyl radicals, including mobile OH radicals. The brookite-nanostructured TiO2 electrode facilitates photocatalyst collection and recycling with excellent stability, and readily controls photocatalytic degradation rates with facile input of additional potential.