In situ Cu single atoms anchoring on MOF-derived porous TiO2 for the efficient separation of photon-generated carriers and photocatalytic H2 evolution.

Single atom catalysts (SACs) have an extremely high atom utilization and distinctive structures and properties in the field of photocatalysis. However, the premise of conducting scientific research and applications is still the stability and catalytic activity of single atoms on suitable substrates. Metal organic frameworks (MOFs), as one of the most suitable single-atom substrates, have tunable internal structures, unsaturated coordination bonds, and high specific surface areas. In this work, Ti-based MOF, MIL-125, was adopted as the precursor to prepare mesoporous Cu-loaded TiO2. During the synthesis of MIL-125, a Cu source was added, and Cu atoms were fixed by partly replacing Ti atoms in the Ti-O octahedron to coordinate with O atoms, resulting in a good dispersity, good stability and high loading amount. Experimental investigations demonstrated that dispersed Cu single atoms act as reaction centres, besides being able to accelerate the transfer of photoelectrons. Under simulated sunlight, the H2 evolution rate of the optimum Cu-TiO2 sample reaches 17.77 mmol g-1 h-1, nearly 101 times higher than that of the pure mesoporous TiO2. The apparent quantum efficiency (AQE) is 20.15% under 365 nm irradiation. This research opens a new thinking to preparing high stability and high activity single atom photocatalysts.

Silver nanoparticles embedded 2D g-C3N4nanosheets toward excellent photocatalytic hydrogen evolution under visible light.

Photocatalytic water splitting is considered to be a feasible method to replace traditional energy. However, most of the catalysts have unsatisfactory performance. In this work, we used a hydrothermal process to grow Ag nanoparticlesin situon g-C3N4nanosheets, and then a high performance catalyst (Ag-g-C3N4) under visible light was obtained. The Ag nanoparticles obtained by this process are amorphous and exhibit excellent catalytic activity. At the same time, the local plasmon resonance effect of Ag can effectively enhance the absorption intensity of visible light by the catalyst. The hydrogen production rate promote to 1035µmol g-1h-1after loaded 0.6 wt% of Ag under the visible light, which was 313 times higher than that of pure g-C3N4(3.3µmol g-1h-1). This hydrogen production rate is higher than most previously reported catalysts which loaded with Ag or Pt. The excellent activity of Ag-g-C3N4is benefited from the Ag nanoparticles and special interaction in each other. Through various analysis and characterization methods, it is shown that the synergy between Ag and g-C3N4can effectively promote the separation of carriers and the transfer of electrons. Our work proves that Ag-g-C3N4is a promising catalyst to make full use of solar energy.

Ultrasensitive ppb-level trimethylamine gas sensor based on p-n heterojunction of Co3O4/WO3.

Trace poisonous and harmful gases in the air have been harming and affecting people's health for a long time. At present, effective and accurate detection of ppb-level harmful gas is still a bottleneck to be overcome. Herein, we report a ppb-level triethylamine (TEA) gas sensor based on p-n heterojunction of Co3O4/WO3, which is prepared with ZIF-67 as the precursor and provides Co3O4deposited tungsten oxide flower-like structure. Due to the introduction of Co3O4and the 3D flower-like structure of WO3, the Co3O4/WO3-2 gas sensor shows excellent gas sensing performance (1101 for 10 ppm at 240 °C), superb selectivity, good long-term stability and linear response for TEA concentration. Moreover, the experimental results indicate that the Co3O4/WO3-2 gas sensor also possesses a good response to 50 ppb TEA, in fact, the theoretical limit of detection is 0.6 ppb. Co3O4not only improves the efficiency of electron separation/transport, but also accelerates the oxidation rate of TEA. This method of synthesizing p-n heterojunction with ZIF as the precursor provides a new idea and method for the preparation of low detection limit gas sensors.

Elevated B-type natriuretic peptide (BNP) and soluble thrombomodulin (sTM) indicates severity and poor prognosis of sepsis.

BACKGROUND: To study the predictive value of B-type natriuretic peptide (BNP) and soluble thrombomodulin (sTM) in the severity stratification and prognosis evaluation of sepsis. METHODS: The clinical data of 137 sepsis patients diagnosed and treated in Sichuan Provincial People's Hospital from May 2018 to November 2020 were retrospectively analyzed. Meanwhile, 121 healthy individuals were selected as the control group. Patients with sepsis were allocated into the mild group, severe group, and shock group according to the severity. According to the 28-day prognosis, the patients were allocated into the death group and survival group. The plasma BNP and serum sTM levels in different groups were compared, and their prognostic value was evaluated. RESULTS: Patients with sepsis had significantly higher levels of BNP and sTM than the healthy control group (P<0.05). The levels of BNP and sTM in the mild group were significantly lower than those in the severe group and shock group, and both BNP and sTM were positively correlated with Acute Physiology and Chronic Health Status (APACHE) II score (r=0.595, 0.516, P<0.05). The levels of BNP and sTM in the death group were significantly higher than those in the survival group (P<0.05). The area under curve (AUC) of BNP combined with sTM was significantly greater than that of BNP or sTM alone for the prognosis of sepsis (P<0.05). When the cut-off value of BNP was 625.68 pg/mL, the sensitivity and specificity were 77.42% and 89.42%, respectively. When the cut-off value of sTM was 10.53 ng/mL, the sensitivity and specificity were 83.87% and 94.34%, respectively. CONCLUSIONS: Patients with sepsis have significantly higher serum BNP and sTM levels which are positively correlated with the severity of the disease. Both of the 2 indexes have good prognostic value, and the predictive value is higher when combined.

DFT calculations for single-atom confinement effects of noble metals on monolayer g-C3N4 for photocatalytic applications.

Graphitic carbon nitride, as a very promising two-dimensional structure host for single atom catalysts (SACs), has been studied extensively due to its significant confinement effects of single atoms for photocatalytic applications. In this work, a systematic investigation of g-C3N4 confining noble metal single atoms (NM1@g-C3N4) will be performed by using DFT calculations. The geometric structure calculations indicate that the most favorable anchored sites for the NM1 is located in the six-fold cavity, and the deformed wrinkle space of g-C3N4 helps the NM1 to be stabilized in the six-fold cavity. The electronic structure calculations show that the conduction band of NM1@g-C3N4 moved down and crossed through the Fermi level, resulting in narrowing the band gap of the NM1@g-C3N4. Moreover, the confined NM1 provide a new channel of charge transport between adjacent heptazine units, resulting in a longer lifetime of photo-generated carriers except Ru, Rh, Os and Ir atoms. Furthermore, the d-band centres of NM1 in NM1@g-C3N4 show that Rh1@, Pd1@, Ir1@ and Pt1@g-C3N4 SACs may have better photocatalytic performance than other NM1@g-C3N4 SACs. Finally, Pt1@g-C3N4 SACs are considered to have higher photocatalytic activity than other NM1@g-C3N4 SACs. These results demonstrate that the confinement effects of noble metals on monolayer g-C3N4 not only makes the single atom more stable to be anchored on g-C3N4, but also enhances the photocatalytic activity of the system through the synergistic effect between the confined NM1 and the monolayer g-C3N4. These detailed research may provide theoretical support for engineers to prepare photocatalysts with higher activity.

The α-Fe2O3/graphite anode composites with enhanced electrochemical performance for lithium-ion batteries.

The α-Fe2O3/graphite composites were prepared by a thermal decomposition method using the expanded graphite as the matrix. The α-Fe2O3 nanoparticles with the size of 15-30 nm were embedded into interlayers of graphite, forming a laminated porous nanostructure with a main pore distribution from 2 to 20 nm and the Brunauer-Emmett-Teller surface area of 33.54 m2 g-1. The porous structure constructed by the graphite sheets can alleviate the adverse effects caused by the huge volume change of the α-Fe2O3 grains during the charge/discharge process. The composite electrode exhibits a high reversible capacity of 1588 mAh g-1 after 100 cycles at 100 mA g-1, 702 mAh g-1 at 5 A g-1, 460 mAh g-1 at 10 A g-1 after 160 cycles, respectively, showing good cycle stability and outstanding rate capability at high current densities.