Solar-driven reduction of CO , which converts inexhaustible solar energy into value-added fuels, has been recognized as a promising sustainable energy conversion technology. However, the overall conversion efficiency is significantly limited by the inefficient charge separation and sluggish interfacial reaction dynamics, which resulted from a lack of sufficient active sites. Herein, Bi O Cl superfine nanotubes with a bilayer thickness of the tube wall are designed to achieve structural distortion for the creation of surface oxygen defects, thus accelerating the carrier migration and facilitating CO activation. Without cocatalyst and sacrificing reagent, Bi O Cl nanotubes deliver high selectivity CO evolution rate of 48.6 μmol g h in water (16.8 times than of bulk Bi O Cl ), while maintaining stability even after 12 h of testing. This paves the way to design efficient photocatalysts with collaborative optimizing charge separation and CO activation towards CO photoreduction.

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Novel carbon quantum dot (CQD) modified Bi2MoO6 photocatalysts were prepared via a facile hydrothermal process. The CQD modified Bi2MoO6 materials were characterized by multiple techniques. The CQDs with the average size of about 7 nm were distributed on the surface of Bi2MoO6 nanosheets. The photocatalytic activity of as-prepared CQD modified Bi2MoO6 materials was investigated sufficiently by the photodegradation of four different kinds of pollutants, such as ciprofloxacin (CIP), bisphenol A (BPA), tetracycline hydrochloride (TC), and methylene blue (MB). The improved photocatalytic activity was observed for CQD modified Bi2MoO6 samples compared with pure Bi2MoO6 under visible light irradiation. The CQD modified Bi2MoO6 photocatalysts with a CQD content of 2 wt% exhibited the optimum photocatalytic activity, which was found to increase by about 5 times than that of the pure Bi2MoO6 for the photodegradation of CIP. This improvement was attributed to the crucial role of CQDs, which acted as a photocenter for absorbing solar light, a charge separation center for suppressing charge recombination, and a catalytic center for pollutant photo-degradation. The main active species were determined to be ˙OH and O˙-(2) by the ESR technique and analyzed by calculations as well as XPS valence spectra, and a possible photocatalytic mechanism was also proposed.

Ammonia (NH3), an important raw material for chemical industry and agriculture, is also considered to be an intriguing energy storage and transportation media for chemical conversion schemes. The world's primary NH3 supply is based on the natural nitrogen fixation by diazotrophs through an enzymatic nitrogenase process and the industrial nitrogen fixation through a traditional Haber–Bosch process. The natural synthesis of NH3 can hardly meet the rapidly growing global demand. Meanwhile, the industrial NH3 production is still dominated by the high‐temperature and high‐pressure reaction between nitrogen and hydrogen (N2 + 3H2 → 2NH3), requiring intensive energy input and generating massive CO2. Therefore, seeking a breakthrough in the development of catalysts toward efficient ammonia synthesis has become the frontier of energy and chemical conversion schemes. This review summarizes and discusses the recent progress on developing new strategies to optimize the efficiency of NH3 production coupled with renewable energy sources, with a specific focus on electrocatalytic and photoelectrocatalytic conversion of N2 to NH3. The most recent advances in the development of catalytic materials, the design of the reaction systems, and the computational insights for electrochemical and photoelectrochemical ammonia synthesis are covered.

In this paper, carbon quantum dots (CQDs) modified BiOCl ultrathin nanosheets photocatalyst was synthesized via a facile solvothermal method. The structures, morphologies, optical properties, and photocatalytic properties were investigated in detail. The photocatalytic activity of the obtained CQDs modified BiOCl ultrathin nanosheets photocatalyst was evaluated by the degradation of bisphenol A (BPA) and rhodamine B (RhB) under ultraviolet, visible, and near-infrared light irradiation. The CQDs/BiOCl materials exhibited significantly enhanced photocatalytic performance as compared with pure BiOCl and the 5 wt % CQDs/BiOCl materials displayed the best performance, which showed a broad spectrum of photocatalytic degradation activity. The main active species were determined to be hole and O2•- under visible light irradiation by electron spin resonance (ESR) analysis, XPS valence spectra, and free radicals trapping experiments. The crucial role of CQDs for the improved photocatalytic activity was mainly attributed to the superior electron transfer ability, enhanced light harvesting, and boosted catalytic active sites.

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Surface defects in semiconductors have a significant role to tune the photocatalytic reactions. However, the dominant studied defect type is oxygen vacancy, and metal cation vacancies are seldom explored. Herein, bismuth vacancies are engineered into BiOBr through ultrathin structure control and employed to tune photocatalytic CO 2 reduction. V Bi -BiOBr ultrathin nanosheets deliver a high selective CO generation rate of 20.1 μmol g −1 h −1 in pure water, without any cocatalyst, photosensitizer, and sacrificing reagent, roughly 3.8 times higher than that of BiOBr nanosheets. The increased CO 2 reduction activity is ascribed to the tuned electronic structure, optimized CO 2 adsorption, activation, and CO desorption process over V Bi -BiOBr ultrathin nanosheets. This work offers new opportunities for designing surface metal vacancies to optimize the CO 2 photoreduction performances.

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