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Photocatalytic hydrogen evolution using inexhaustible clean solar energy is considered as a promising strategy. In order to build an efficient photocatalytic hydrogen production system to satisfy the demands of practical applications, it is of great significance to design photocatalysts that offer high activity, low cost, and high stability. Herein, a series of cheap CdS/Ni(OH)2 composite photocatalysts were designed and synthesized using the hydrothermal method. The introduction of a Ni(OH)2 cocatalyst multiplied the reactive active site of cadmium sulfide and promoted the transfer of photoinduced electrons in a semiconductor. Therefore, CdS/Ni(OH)2 composites demonstrate significantly better photocatalytic performance, and the hydrogen production rate of an optimal CdS/5%Ni(OH)2 composite is 6.9 times higher than that of blank CdS. Furthermore, the stability test also showed that CdS/Ni(OH)2 had good stability. This study aims to serve as a rewarding reference for the development of high-performance composite photocatalysts. [ABSTRACT FROM AUTHOR]

The development of efficient and environmentally friendly photocatalysts is crucial for addressing global energy and environmental challenges. Perylene diimide, an organic supramolecular material, holds great potential for applications in mineralized phenol. In this study, through the integration of different mass ratios of unmodified perylenimide (PDI-NH) into the self-assembly of amino acid-substituted perylenimide (PDI-COOH), a novel supramolecular organic heterojunction (PDICOOH/PDINH) was fabricated. The ensuing investigation focuses on its visible-light mineralized phenol properties. The results show that the optimal performance is observed with a composite mass fraction of 10%, leading to complete mineralization of 5 mg/L phenol within 5 h. The reaction exhibits one-stage kinetics with rate constants 13.80 and 1.30 times higher than those of PDI-NH and PDI-COOH, respectively. SEM and TEM reveal a heterogeneous interface between PDI-NH and PDI-COOH. Photoelectrochemical and Kelvin probe characterization confirm the generation of a built-in electric field at the interface, which is 1.73 times stronger than that of PDI-COOH. The introduction of PDI-NH promotes π-π stacking of PDI-COOH, while the built-in electric field facilitates efficient charge transfer at the interface, thereby enhancing phenol decomposition. The finding demonstrates that supramolecular heterojunctions have great potential as highly effective photocatalysts for environmental remediation applications. [ABSTRACT FROM AUTHOR]

Developing artificial N2 fixation and hydrogen production using mild, green, clean, and reliable sunlight is of great significance. In this study, the photocatalytic nitrogen fixation and hydrogen production performances of WO3−x were improved by oxygen vacancies engineering. WO3−x nanosheets with oxygen-rich defects were readily synthesized by hydrogen reduction treatment. WO3−x exhibits a two-dimensional nanosheets structure, and the introduction of oxygen defects affects its energy band structure. The slight narrowing of the band gap and the increase of the conduction band facilitate the transfer of photogenerated charges and increase the reducibility of WO3−x. Electron paramagnetic resonance (EPR) and N2-temperature programmed desorption (N2-TPD) prove that oxygen vacancies can regulate the adsorption and activation of N2 molecules. W500 specimen has a photocatalytic nitrogen fixation activity of 28.4 μmol g−1 h−1 and a hydrogen production activity of 60.4 μmol g−1 h−1 under the full spectrum. It is hoped that oxygen vacancies engineering can provide some inspiration for the rational design and optimization of efficient photocatalytic fixation of N2 and hydrogen production. [ABSTRACT FROM AUTHOR]

The green and clean sunlight-driven catalytic conversion of CO2 into high-value-added chemicals can simultaneously solve the greenhouse effect and energy problems. The controllable preparation of semiconductor catalyst materials and the study of refined structures are of great significance for the in-depth understanding of solar-energy-conversion technology. In this study, we prepared nitrogen-doped NiO semiconductors using a one-pot molten-salt method. The research shows that the molten-salt system made NiO change from p-type to n-type. In addition, nitrogen doping enhanced the adsorption of CO2 on NiO and increased the separation of photogenerated carriers on the NiO. It synergistically optimized the CO2-reduction system and achieved highly active and selective CO2 photoreduction. The CO yield on the optimal nitrogen-doped photocatalyst was 235 μmol·g−1·h−1 (selectivity 98%), which was 16.8 times that of the p-type NiO and 2.4 times that of the n-type NiO. This can be attributed to the fact that the nitrogen doping enhanced the oxygen vacancies of the NiOs and their ability to adsorb and activate CO2 molecules. Photoelectrochemical characterization also confirmed that the nitrogen-doped NiO had excellent electron -transfer and separation properties. This study provides a reference for improving NiO-based semiconductors for photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

Photocatalysis has been regarded as a promising technology for degrading organic pollutants in wastewater and producing hydrogen. In this paper, TiO2 nanoparticles (NPs) were synthesized to improve the visible light absorption of TiO2, which were further combined with Bi2O3 nanosheets to synthesize a series of 0D/2D TiO2 NPs/Bi2O3 nanosheet heterojunctions. The visible light induced photocatalytic activities of the as-synthesized TiO2/Bi2O3 heterojunctions were studied. The optimized catalyst TB-3 with 15 wt% of Bi2O3/TiO2 exhibited the best photocatalytic degradation of tetracycline hydrochloride (TC). The degradation rate constant k of TC over TB-3 was approximately eight times and 39 times greater than that of P25 and Bi2O3, respectively. Additionally, TB-3 showed the highest amount of hydrogen evolution, while that of Bi2O3 was almost zero. The enhancement of photocatalytic performances was ascribed to the improved visible light absorption and the Z-scheme charge transfer path of the TiO2/Bi2O3 heterojunctions, which enhanced the separation efficiency and reduced recombination of photogenerated charge carries, as evidenced by UV–Visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electrochemistry measurements. The active species trapping experiments and the electron spin resonance (ESR) results revealed that ·O2− was the main active substance in the photocatalytic degradation. The possible degradation pathway and intermediate products of TC have been proposed. This work provides experimental evidence supporting the construction of Z-scheme heterojunctions to achieve excellent visible light induced photocatalytic activity. [ABSTRACT FROM AUTHOR]