ABSTRACT
Carrier spatial separation efficiency and active electron density are the key factors affecting photocatalytic hydrogen evolution activity. Heterojunction catalysts with fast charge separation and directed electron transport systems were successfully prepared by a synergistic modification strategy of transition metal (Co) doping and crystal plane modulation. The optimized electronic structure and enhanced reaction kinetics enabled unidirectional electron transfer. Photocatalytic results show that CdS(002)/Co-C3N4 exhibits remarkable hydrogen evolution activity (991.2 µmol h-1 g-1) in the absence of a co-catalyst, which is 37.0 and 3.4 times higher than that of C3N4 (26.8 µmol h-1 g-1) and Co-C3N4 (294.6 µmol h-1 g-1), respectively. Density functional theory (DFT) calculations indicate that the enhanced catalytic activity of CdS(002)/Co-C3N4 is attributed to the reduced electron-hole recombination rate and the increased electron density at the active site. This work provides a new idea for the design of photocatalysts with directed charge transport channels from the perspective of re-optimizing heterojunctions.
ABSTRACT
The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C3N4) are the main obstacles to its application in photocatalytic CO2 reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H3PO4), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C3N4. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C3N4 can reach 13.55 µmol g-1 h-1, which was 3.9 times higher than that of g-C3N4 (3.49 µmol g-1 h-1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C3N4 can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C3N4. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C3N4 photocatalytic materials.
ABSTRACT
Photocatalytic removal of nitrate in wastewater has attracted wide attention because of its simple operation and environmental protection. However, the preparation of photocatalysts with high efficiency and high nitrogen selectivity is still a challenge. In this paper, TiO2 is grown in situ on Ti3C2 MXene by a simple calcination method and modified with silver particles. The presence of Ti3C2 reduces the recombination rate of photogenerated electrons and generates more photogenerated electrons. At the same time, the silver particles also increase the photoelectron density and further improve the carrier separation of the catalyst. Due to its unique structure and optical properties, the prepared photocatalyst shows an excellent nitrate removal rate under a high-pressure mercury lamp. At 500 mgN/L, the nitrate removal rate reaches 96.1%, and the nitrogen selectivity reaches 92.6%. Even after 5 cycles, the prepared photocatalyst still maintains a high nitrate photocatalytic removal efficiency (89%). The electron transfer path is verified by density functional theory calculations.
ABSTRACT
The antidiuretic hormone vasopressin (AVP), acting through its type 2 receptor (V2R) in the collecting duct (CD), critically controls urine concentrating capability. Here, we report that site-1 protease-derived (S1P-derived) soluble (pro)renin receptor (sPRR) participates in regulation of fluid homeostasis via targeting V2R. In cultured inner medullary collecting duct (IMCD) cells, AVP-induced V2R expression was blunted by a PRR antagonist, PRO20; a PRR-neutralizing antibody; or a S1P inhibitor, PF-429242. In parallel, sPRR release was increased by AVP and reduced by PF-429242. Administration of histidine-tagged sPRR, sPRR-His, stimulated V2R expression and also reversed the inhibitory effect of PF-429242 on the expression induced by AVP. PF-429242 treatment in C57/BL6 mice impaired urine concentrating capability, which was rescued by sPRR-His. This observation was recapitulated in mice with renal tubule-specific deletion of S1P. During the pharmacological or genetic manipulation of S1P alone or in combination with sPRR-His, the changes in urine concentration were paralleled with renal expression of V2R and aquaporin-2 (AQP2). Together, these results support that S1P-derived sPRR exerts a key role in determining renal V2R expression and, thus, urine concentrating capability.
