Unraveling the atomic-level vacancy modulation in Cu9S5 for NIR-driven efficient inhibition of drug-resistant bacteria: Key role of Cu vacancy position.

Cu9S5 possesses high hole concentration and potential superior electrical conductivity as a novel p-type semiconductor, whose biological applications remain largely unexploited. Encouraged by our recent work that Cu9S5 has enzyme-like antibacterial activity in the absence of light, which may further enhance the near infrared (NIR) antibacterial performance. Moreover, vacancy engineering can modulate the electronic structure of the nanomaterials and thus optimize their photocatalytic antibacterial activities. Here, we designed two different atomic arrangements with same VCuSCu vacancies of Cu9S5 nanomaterials (CSC-4 and CSC-3) determined by positron annihilation lifetime spectroscopy (PALS). Aiming at CSC-4 and CSC-3 as a model system, for the first time, we investigated the key role of different copper (Cu) vacancies positions in vacancy engineering toward optimizing the photocatalytic antibacterial properties of the nanomaterials. Combined with the experimental and theoretical approach, CSC-3 exhibited stronger absorption energy of surface adsorbate (LPS and H2O), longer lifetime of photogenerated charge carriers (4.29 ns), and lower reaction active energy (0.76 eV) than those of CSC-4, leading to the generation of abundant ·OH for attaining rapid drug-resistant bacteria killed and wound healed under NIR light irradiation. This work provided a novel insight for the effective inhibition of drug-resistant bacteria infection via vacancy engineering at the atomic-level modulation.

Boosted Photoreforming of Plastic Waste via Defect-Rich NiPS3 Nanosheets.

Sustainable conversion of plastic waste to mitigate environmental threats and reclaim waste value is important. Ambient-condition photoreforming is practically attractive to convert waste to hydrogen (H2); however, it has poor performance because of mutual constraint between proton reduction and substrate oxidation. Here, we realize a cooperative photoredox using defect-rich chalcogenide nanosheet-coupled photocatalysts, e.g., d-NiPS3/CdS, to give an ultrahigh H2 evolution of ∼40 mmol gcat-1 h-1 and organic acid yield up to 78 µmol within 9 h, together with excellent stability beyond 100 h in photoreforming of commercial waste plastic poly(lactic acid) and poly(ethylene terephthalate). Significantly, these metrics represent one of the most efficient plastic photoreforming reported. In situ ultrafast spectroscopic studies confirm a charge transfer-mediated reaction mechanism in which d-NiPS3 rapidly extracts electrons from CdS to boost H2 evolution, favoring hole-dominated substrate oxidation to improve overall efficiency. This work opens practical avenues for converting plastic waste into fuels and chemicals.

Vacancy-cluster-mediated surface activation for boosting CO2 chemical fixation.

The cycloaddition of CO2 with epoxides towards cyclic carbonates provides a promising pathway for CO2 utilization. Given the crucial role of epoxide ring opening in determining the reaction rate, designing catalysts with rich active sites for boosting epoxide adsorption and C-O bond cleavage is necessary for gaining efficient cyclic carbonate generation. Herein, by taking two-dimensional FeOCl as a model, we propose the construction of electron-donor and -acceptor units within a confined region via vacancy-cluster engineering to boost epoxide ring opening. By combing theoretical simulations and in situ diffuse reflectance infrared Fourier-transform spectroscopy, we show that the introduction of Fe-Cl vacancy clusters can activate the inert halogen-terminated surface and provide reactive sites containing electron-donor and -acceptor units, leading to strengthened epoxide adsorption and promoted C-O bond cleavage. Benefiting from these, FeOCl nanosheets with Fe-Cl vacancy clusters exhibit enhanced cyclic carbonate generation from CO2 cycloaddition with epoxides.

Effect of electroacupuncture on the intestinal microflora in rats with stress urinary incontinence.

Objective: To examine the effect of electroacupuncture on the urodynamics and gut microbiota of rats with stress urinary incontinence (SUI). Materials and methods: Thirty 2-month-old female Sprague-Dawley (SD) rats were randomly assigned to 4 groups: normal (N), model (M), nonacupoint electric acupuncture control (NAAC), and electroacupuncture (EA). An SUI rat model was established through vaginal balloon dilatation and bilateral oophorectomy. After various treatments, urodynamic tests were performed, and feces were collected. 16S rRNA sequencing analysis was used to investigate SUI-related changes in the intestinal flora. Results: After treatment, compared with those of the M group, the leak point pressure and maximum bladder capacity of the electroacupuncture groups increased (P<0.05). The species community compositions of the N and M groups differed at the genus level, and there were 15 differentially abundant bacterial genera (P<0.05). The Blautia proportion was increased by electroacupuncture treatment (P<0.05) and was significantly positively correlated with the electroacupuncture treatment of SUI (according to Spearman correlation analysis). Conclusion: Electroacupuncture treatment can improve signs of urine leakage in rats with SUI rats by increasing the leak point pressure and maximum bladder capacity. The enrichment of Blautia by electroacupuncture treatment enrichment may be related to SUI sign improvement.

Highly Ion-Permselective Porous Organic Cage Membranes with Hierarchical Channels.

Membranes of high ion permselectivity are significant for the separation of ion species at the subnanometer scale. Here, we report porous organic cage (i.e., CC3) membranes with hierarchical channels including discrete internal cavities and cage-aligned external cavities connected by subnanometer-sized windows. The windows of CC3 sieve monovalent ions from divalent ones and the dual nanometer-sized cavities provide pathways for fast ion transport with a flux of 1.0 mol m-2 h-1 and a mono-/divalent ion selectivity (e.g., K+/Mg2+) up to 103, several orders of magnitude higher than the permselectivities of reported membranes. Molecular dynamics simulations illustrate the ion transport trajectory from the external to internal cavity via the CC3 window, where ions migrate in diverse hydration states following the energy barrier sequence of K+ < Na+ < Li+ ≪ Mg2+. This work sheds light on ion transport properties in porous organic cage channels of discrete frameworks and offers guidelines for developing membranes with hierarchical channels for efficient ion separation.

Dual confinement of high-loading enzymes within metal-organic frameworks for glucose sensor with enhanced cascade biocatalysis.

The intrinsically fragile nature and leakage of the enzymes is a major obstacle for the commercial sensor of a continuous glucose monitoring system. Herein, a dual confinement effect is developed in a three dimensional (3D) nanocage-based zeolite imidazole framework (NC-ZIF), during which the high-loading enzymes can be well encapsulated with unusual bioactivity and stability. The shell of NC-ZIF sets the first confinement to prevent enzymes leakage, and the interior nanocage of NC-ZIF provides second confinement to immobilize enzymes and offers a spacious environment to maintain their conformational freedom. Moreover, the mesoporosity of the formed NC-ZIF can be precisely controlled, which can effectively enhance the mass transport. The resulted GOx/Hemin@NC-ZIF multi-enzymes system could not only realize rapid detection of glucose by colorimetric and electrochemical sensors with high catalytic cascade activity (with an 8.3-fold and 16-fold enhancements in comparison with free enzymes in solution, respectively), but also exhibit long-term stability, excellent selectivity and reusability. More importantly, the based wearable sweatband sensor measurement results showed a high correlation (>0.84, P < 0.001) with the levels measured by commercial glucometer. The reported dual confinement strategy opens up a window to immobilize enzymes with enhanced catalytic efficiency and stability for clinical-grade noninvasive continuous glucose sensor.

Recent advances in biological applications of nanomaterials through defect engineering.

In recent years, defect engineering sprung up in the artificial nanomaterials (NMs) has attracted significant attention, since the physical and chemical properties of NMs could be largely optimized based on the rational control of different defect types and densities. Defective NMs equipped with the improved electric and catalytic ability, would be widely utilized as the photoelectric device and catalysts to alleviate the growing demands of industrial production and environmental treatments. In particular, considering that the features of targeting, adsorptive, loading and optical could be adjusted by the introduction of defects, numerous defective NMs are encouraged to be applied in the biological fields including bacterial inactivation, cancer therapy and so on. And this review is devoted to summarize the recent biological applications of NMs with abundant defects. Moreover, the opportunity of these defective NMs released into the surrounding environment continue to increase, the direct and indirect contact with biological molecules and organisms would be inevitable. Due to its high reactivity and adsorption triggered by defects, NMs tend to exhibit overestimate biological behaviors and effects on organisms. Thus, the sections regarding toxicological effects of NMs with abundant defects are also carried out to supplement the safety assessments of NMs and guide further applications in the industrial production and living.

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu2Se.

In this study, a series of Cu2+x-yInySe (-0.3 ≤ x ≤ 0.2 and 0 ≤ y ≤ 0.05) samples were prepared by melting and the spark plasma sintering method. X-ray diffraction measurements indicate that the Cu-deficient samples (x = -0.3 y = 0 and x = -0.2 y = 0) prefer to form the cubic phase (ß-Cu2Se). Adding excessive Cu or introducing In atoms into the Cu2Se matrix triggers a phase transition from the ß to α phase. Positron lifetime measurements confirm the reduction in Cu vacancy concentration by adding excessive Cu or introducing In atoms into Cu2Se, which causes a dramatic decrease in carrier concentration from 1.59 × 1021 to 5.0 × 1019 cm-3 at room temperature. The samples with In contents of 0.01 and 0.03 show a high power factor of about 1 mW m-1 K-2 at room temperature due to the optimization of the carrier concentration. Meanwhile, the excess Cu content and doping of In atoms also favor the formation of nanopores. These pores have strong interaction with phonons, leading to remarkable reduction in lattice thermal conductivity. Finally, a high ZT value of about 1.44 is achieved at 873 K in the Cu1.99In0.01Se (x = 0 and y = 0.01) sample, which is about twice that of the Cu-deficient sample (Cu1.7Se). Our work provides a viable insight into tuning vacancy defects to improve efficiently the electrical and thermal transport performance for copper-based thermoelectric materials.

[Effect of electroacupuncture on expression of p-ERK1/2 and c-fos in spinal dorsal horn in rats with interstitial cystitis].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at "Ciliao" (BL32) and "Huiyang" (BL35) on the expression of extracellular signal-regulated kinase 1/2 (p-ERK1/2) and cellular oncogene fos (c-fos) phosphorylated of spinal dorsal horn in rats with interstitial cystitis (IC). METHODS: Eighteen female Wistar rats were randomly divided into control, model and EA groups, with 6 rats in each group. The IC model was established by intraperitoneal injection of cyclophosphamide (150 mg/kg). EA (30 Hz, 1 mA) was applied to bilateral BL32 and BL35 for 20 min, once daily for 3 consecutive days. The bladder pain was measured by using a Von Frey at 48 h after modeling and 24 h after EA. The expression levels of p-ERK1/2 and c-fos protein in L6-S1 segment of spinal cord were detected by Western blot, and the expression of p-ERK1/2 and c-fos in the right spinal dorsal horn were displayed by immunofluorescence staining. RESULTS: After modeling, the bladder mechanical pain threshold (PT) was significantly decreased (P<0.05), the protein expression of p-ERK1/2 and c-fos in the spinal cord was increased (P<0.05) and the immunofluorescence surface density of p-ERK1/2 and c-fos in the right dorsal horn of spinal cord was increased (P<0.05) in the model group relevant to the control group. After EA intervention, IC-induced reduction of PT, and increases of the expression of p-ERK1/2 and c-fos as well as immunofluorescence surface density of p-ERK1/2 and c-fos were reversed in the EA group relevant to the model group (P<0.05). CONCLUSION: EA at BL 32 and BL 35 has an analgesic effect in IC rats, which may be related to its effect in down-regulating the expression of p-ERK1/2 and c-fos in spinal dorsal horn.

Less is more: biological effects of NiSe2/rGO nanocomposites with low dose provide new insight for risk assessment.

Nickel selenide nanomaterials (NiSe2 NMs) with different vacancies demonstrated high catalytic activity as electrocatalyst in oxygen evolution reaction. As the growing needs of the industrial applications in electrocatalyst, the increased occupational exposure and environmental releasing of NMs would be unavoidable. While, much efforts have been made to evaluate the ecological safety of such engineered NMs at unrealistically high concentrations, failed to provide the comprehensively guideline for exposure thresholds. To supplement the current knowledge gap, we testified the cytotoxicity of NiSe2/rGO nanocomposites with different surface defects under more realistic exposure mode. Compared with the short-term exposure and repetitive exposure, rat lung macrophages exhibited the augmented oxidative stress, dysfunction of mitochondria, damage of DNA and disorder of calcium homeostasis under the long-term NiSe2/rGO exposure. Noteworthily, no significant differences could be found between the NiSe2/rGO with different surface defects, indicated that the defect type of NMs were not the accurate predictor for real risk assessment. Collectively, the study provided the real potential toxic effects and exposure thresholds of NMs that might be highly possible industrial produced, and appealed the new insight for risk assessments of engineered NMs under the long-term exposure, which exhibited difference from the traditional evaluation of short-term and repetitive exposure.

Effects of Electroacupuncture on Ovarian Expression of the Androgen Receptor and Connexin 43 in Rats with Letrozole-Induced Polycystic Ovaries.

BACKGROUND: Polycystic ovarian syndrome (PCOS) occurs in women of reproductive age and is often characterized by reproductive and endocrine dysfunction. Androgens play a major role in PCOS, and previous studies reported abnormal expression of Connexin 43 (Cx43) in animal models of PCOS, suggesting an association of Cx43 with PCOS pathogenesis. Experimental and clinical evidence indicated that acupuncture may be a safe and effective approach for treating reproductive and endocrine disorders in women with PCOS. This study aimed to determine the effects of electroacupuncture (EA) on PCOS and its relationship with the expression of the androgen receptor (AR) and Cx43. METHODS: In total, 30 female Sprague Dawley rats (6 weeks old) were randomly divided into three groups: control group, letrozole (LE) group, and LE + EA group. Rats were administered LE solution (1.0 mg/kg) for 21 consecutive days to induce PCOS. For the LE + EA group, additional EA treatment was conducted (2 Hz, 20 min/d) with "Guanyuan" (CV3) for 14 consecutive days. After hematoxylin-eosin staining, the ovarian structure was observed with an optical microscope, and serum levels of the following hormones were examined via enzyme-linked immunosorbent assay (ELISA): testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH); luteinizing hormone (LH), insulin (INS), anti-Müllerian hormone (AMH), and inhibin B (INHB). Fasting blood glucose (FBG) levels were evaluated using glucose oxidase-peroxidase. Ovarian mRNA and protein expressions of AR and Cx43 were determined by real-time RT-PCR and Western blot analysis. RESULTS: EA was found to restore the cyclicity and ovarian morphology in the PCOS rat model. Serum derived from the LE + EA group showed significant decreases in the levels of T, free androgen index (FAI), LH, LH/FSH ratio, AMH, INHB, and fasting serum insulin (FINS), and significant increases in the levels of E2, FSH, and SHBG. Western blot analysis showed a decreased protein expression of ovarian AR and Cx43; real-time RT-PCR showed reduced expression of ovarian mRNA levels of AR and Cx43. CONCLUSIONS: In conclusion, our results showed that EA can ease hyperandrogenism and polycystic ovary morphology in PCOS rats. Furthermore, EA counteracted the letrozole-induced upregulation of AR and Cx43. These results suggested that acupuncture can break the vicious cycle initiated by excessive androgen secretion and may be an effective treatment method for improving the reproductive and endocrine dysfunction caused by PCOS.

Mechanism of upconversion luminescence enhancement in Yb3+/Er3+ co-doped Y2O3 through Li+ incorporation.

Li+ doping is a well-known, simple, yet efficient strategy to optimize the properties of upconverting materials. Nonetheless, the position of Li+ in the lattice and the mechanism of upconversion enhancement are still controversial, especially in Yb3+/Er3+ co-doped Y2O3. This paper presents a comprehensive investigation of the above issues (i.e. the position occupied by Li+ in the lattice and the mechanism of luminescence enhancement, in terms of decreased defects) by studying (Y0.78-XYb0.20Er0.02LiX)2O3 powders. Neutron powder diffraction was employed for the first time in the literature to show that Li+ ions are accommodated in Y sites of YO6 octahedra, confirmed also by the content of oxygen defects, which was increased with the increase of Li+ concentration. FT-IR showed that there was a small change in the amount and the type of the surface-absorbed groups with the increase in the Li+ content, thus not supporting the prevailing conclusion that the quenching groups are decreased by doping Li+. Positron annihilation lifetime (PLAS) experiments showed that the total defect concentration and the large defect clusters, which are considered as quenching centers, are decreased with increasing Li+-content, resulting in the enhancement of the emission intensity in Yb3+/Er3+ co-doped Y2O3.

Enhancement of Solar-Driven Photocatalytic Activity of BiOI Nanosheets through Predominant Exposed High Energy Facets and Vacancy Engineering.

The increasing application of exposed high energy facet is an effective strategy to improve the photocatalytic performance of photocatalysts because the vacancies are beneficial to photocatalytic reaction. Vacancy dominates numerous distinct properties of semiconductor materials and thus plays a conclusive role in the photocatalysis applications. In this work, two kinds of BiOI nanomaterials with different vacancies are synthesized via a facile solvothermal method. The positron annihilation analysis shows that the thinner BiOI nanosheets possess larger-sized vacancy than BiOI nanoplates. Thus, BiOI nanosheets show the enhanced separation efficiency of electron-hole pairs and adsorption ability for contaminants under visible light. The results are also validated with the first-principle computation. Therefore, higher photocatalytic activity to the photodegradation of tetracycline is observed from the nanosheets than that obtained from BiOI nanoplates. This work not only arouses attention to vacancies, but also opens up an avenue for precision design of vacancies to prepare novel photocatalytic materials driven under solar light.

Tuning the size of photo-deposited metal nanoparticles via manipulating surface defect structures of TiO2 nanocrystals.

Here we report a new method for controlling photo-deposited metal nanoparticle size by manipulating surface defect structures of TiO2 nanocrystals. Our results demonstrate that the isolated oxygen vacancy could serve as an electron trapper while the oxygen vacancy cluster could act as an electron-hole recombination site in the photo-deposition process.

[Effect of electroacupuncture at different acupoints on follicle development and related factors in serum and ovary tissues of PCOS rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at different acupoints on follicle development, expression of gonadotropins and their receptors and anti-Müllerian hormone(AMH), inhibin B(INHB) in polycystic ovarian syndrome (PCOS) rats, so as to explore its mechanisms underlying improvement of PCOS. METHODS: Sixty female SD rats were randomized into six groups: control, model, Zusanli(ST36), Sanyinjiao(SP6), Guanyuan(CV4) and combination (ST36+SP6+CV4, n=10 rats/group). The PCOS model was established by gavage of Letrozole solution (1.0 mg/kg) once daily for 21 consecutive days. Rats of the control group were given 1% Carboxymethyl Cellulose (CMC, 1 mg/kg). EA (2 Hz) was applied to ST36, SP6, or/and CV4 for 20 min, once daily for 14 consecutive days. The number of follicles was counted, and the ovarian structure and follicular development were observed under light microscope after H.E. stain, and the contents of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), AMH, and INHB were assayed by enzyme-linked immunosorbent assay, and the ratio of LH/FSH was calcula-ted. The immunoactivity of LH receptor (LHR) and FSH receptor (FSHR) proteins was detected by immunohistochemistry. RESULTS: After modeling, the number of follicles at the growth stage, contents of serum LH, AMH and INHB, and ratio of LH/FSH were significantly increased, and serum FSH level and FSHR, LHR immunoactivity were remarkably decreased in the model group relevant to the control group (P<0.05, P<0.01). Following EA intervention, the number of follicles at the growth stage in the SP6, CV4 and combination groups, LH/FSH ratio and serum AMH levels in the 4 EA groups, INHB contents in the ST36, CV4 and combination groups were significantly reduced (P<0.05, P<0.01), while serum FSH contents in the 4 EA groups, FSHR immunoactivity at the early stage in the ST36 group and LHR immunoactivity at both early and late stages in the ST36 and CV4 groups were considerably increased in comparison with those of the model group (P<0.01, P<0.05). The therapeutic effect of SP6 was significantly superior to that of CV4 in down-regulating serum LH level (P<0.01), but significantly inferior to that of CV4 in up-regulating serum FSH content and in down-regulating LH/FSH ratio and serum AMH and INHB levels (P<0.05, P<0.01). The effect of CV4 was comparable to that of ST36 in up-regulating serum FSH, and in down-regulating serum LH/FSH ratio, AMH and INHB levels (P>0.05). CONCLUSION: EA of CV4, SP6, ST36 and ST36+CV4+SP6 can reduce the number of follicles at the growth stage and regulate the expression levels of gonadotropins in PCOS rats. The effects of EA of CV4 and ST36 are evidently better than those of EA of SP6 in up-regulating serum FSH content and in down-regulating LH/FSH ratio, and serum AMH and INHB levels, and EA of SP6 is evidently superior to EA of CV4 down-regulating LH level, but without synergistic effect among the 3 acupoints.

Evolution of the Intrinsic Point Defects in Bismuth Telluride-Based Thermoelectric Materials.

In polycrystalline bismuth telluride-based thermoelectric materials, mechanical-deformation-induced donor-like effects can introduce a high concentration of electrons to change the thermoelectric properties through the evolution of intrinsic point defects. However, the evolution law of these point defects during sample preparation remains elusive. Herein, we systematically investigate the evolution of intrinsic point defects in n-type Bi2Te3-based materials from the perspective of thermodynamics and kinetics, in combination with positron annihilation measurement. It is found that not only the mechanical deformation but also the sintering temperature is vital to the donor-like effect. The mechanical deformation can promote the formation of cation vacancies and facilitate the donor-like effect, and the sintering process can provide excess energy for Bi antisite atoms to surmount the diffusion potential barrier. This work provides us a better understanding of the evolution law of intrinsic point defects in Bi2Te3-based alloys and guides us to control the carrier concentration by manipulating intrinsic point defects.

Defective [Bi2 O2 ]2+ Layers Exhibiting Ultrabroad Near-Infrared Luminescence.

Aurivillius phases have been routinely known as excellent ferroelectrics and have rarely been deemed as materials that luminesce in the near-infrared (NIR) region. Herein, it is shown that the Aurivillius phases can demonstrate broadband NIR luminescence that covers telecommunication and biological optical windows. Experimental characterization of the model system Bi2.14 Sr0.75 Ta2 O9-x , combined with theoretical calculations, help to establish that the NIR luminescence originates from defective [Bi2 O2 ]2+ layers. Importantly, the generality of this finding is validated based on observations of a rich bank of NIR luminescence characteristics in other Aurivillius phases. This work highlights that incorporating defects into infinitely repeating [Bi2 O2 ]2+ layers can be used as a powerful tool to space-selectively impart unusual luminescence emitters to Aurivillius-phase ferroelectrics, which not only offers an optical probe for the examination of defect states in ferroelectrics, but also provides possibilities for coupling of the ferroelectric property with NIR luminescence.

Location determination of metal nanoparticles relative to a metal-organic framework.

Metal nanoparticles (NPs) stabilized by metal-organic frameworks (MOFs) have been intensively studied in recent decades, while investigations on the location of guest metal NPs relative to host MOF particles remain challenging and very rare. In this work, we have developed several characterization techniques, including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) tomography, hyperpolarized 129Xe NMR spectroscopy and positron annihilation spectroscopy (PAS), which are able to determine the specific location of metal NPs relative to the MOF particle. The fine PdCu NPs confined inside MIL-101 exhibit excellent catalytic activity, absolute selectivity and satisfied recyclability in the aerobic oxidation of benzyl alcohol in pure water. As far as we know, the determination for the location of metal NPs relative to MOF particles and pore structure information of metal NPs/MOF composites by 129Xe NMR and PAS techniques has not yet been reported.

Unconventional CN vacancies suppress iron-leaching in Prussian blue analogue pre-catalyst for boosted oxygen evolution catalysis.

The incorporation of defects, such as vacancies, into functional materials could substantially tailor their intrinsic properties. Progress in vacancy chemistry has enabled advances in many technological applications, but creating new type of vacancies in existing material system remains a big challenge. We show here that ionized nitrogen plasma can break bonds of iron-carbon-nitrogen-nickel units in nickel-iron Prussian blue analogues, forming unconventional carbon-nitrogen vacancies. We study oxygen evolution reaction on the carbon-nitrogen vacancy-mediated Prussian blue analogues, which exhibit a low overpotential of 283 millivolts at 10 milliamperes per square centimeter in alkali, far exceeding that of original Prussian blue analogues and previously reported oxygen evolution catalysts with vacancies. We ascribe this enhancement to the in-situ generated nickel-iron oxy(hydroxide) active layer during oxygen evolution reaction, where the Fe leaching was significantly suppressed by the unconventional carbon-nitrogen vacancies. This work opens up opportunities for producing vacancy defects in nanomaterials for broad applications.

Enhancement of Photocatalytic Activity of Bi2 O3 -BiOI Composite Nanosheets through Vacancy Engineering.

Vacancy engineering is an effective strategy to enhance solar-driven photocatalytic performance of semiconductors. It is highly desirable to improve the photocatalytic performance of composite nanomaterials by the introduction of vacancies, but the role of vacancies and the heterostructure in the photocatalytic process is elusive to the composite nanomaterials. Herein, the introduction of I vacancies can significantly enhance the photocatalytic activity of Bi2 O3 -BiOI composite nanosheets in a synergistic manner. The excellent photocatalytic performance of the Bi2 O3 -BiOI composites is attributed to the combination of Bi2 O3 and BiOI and the existence of I vacancies in Bi2 O3 -BiOI composites. Specifically, density functional theory calculation shows that the existence of I vacancies would create a new electric states vacancy band below the conduction band of BiOI and thus can reduce the bandgap of BiOI nanosheets. This greatly facilitates the scavenging of the photogenerated electron on the surface of BiOI by Bi2 O3 , therefore, enhancing the overall photocatalytic activity of the composites. The enhanced photocatalytic efficiency is demonstrated by the degradation of tetracycline (TC), which reaches 96% after 180 min and by the high total organic carbon (TOC) removal (89% after 10 h visible light irradiation). This study provides a novel approach for the design of high-performance composite catalysts.