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[Display omitted] In the present study, an innovative carbon self-doped g-C 3 N 4 (CCN) loaded with ultra-low CeO 2 (0.067–0.74 wt%) composite photocatalyst is successfully synthesized via a facile one-pot hydrothermal and calcination method. The CeO 2 /CCN exhibits superior photocatalytic performance for tetracycline degradation (78.9% within 60 min), H 2 O 2 production (151.92 μmol L-1 within 60 min), and Cr(VI) reduction (99.5% within 40 min), which much higher than that of g-C 3 N 4 , CCN, CeO 2 , and CeO 2 /g-C 3 N 4. The enhanced photocatalytic performance is originated from the fact that the doping of C can efficaciously broaden the utilization range of solar light and improve the reduction ability of photogenerated electrons. Meanwhile, the ultra-low loading of CeO 2 can effectually promote the migration of photogenerated electrons and enhance the specific surface area. Besides, the experiments of pH effect and cycle ability indicate that CeO 2 /CCN has excellent durability and stability. Finally, the photocatalytic mechanism of CeO 2 /CCN is systematically discussed. This work proves that combining element doping and semiconductor coupling is a promising strategy to design high-efficiency g-C 3 N 4 -based photocatalysts. [ABSTRACT FROM AUTHOR]

At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor-based photocatalysis technology, an idea and continuable technology by solar-light-driven, is widely employed to address this situation. Here, oxygen-vacancy rich WO 3 decorated monolayer Bi 2 WO 6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale V o -WO 3 /Bi 2 WO 6 composite displayed remarkable photoactivity comparing with pristine V o -WO 3 and Bi 2 WO 6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L). The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin V o -WO 3 nanosheet decorated monolayer Bi 2 WO 6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via [(LC-MS)/MS]. After 5 run for the degradation of CIP, V o -WO 3 /Bi 2 WO 6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability. [ABSTRACT FROM AUTHOR]

Photocatalysis is currently a hot research field, which provides promising processes to produce green energy sources and other useful products, thus eventually benefiting carbon emission reduction and leading to a low-carbon future. The development and application of stable and efficient photocatalytic materials is one of the main technical bottlenecks in the field of photocatalysis. Perovskite has excellent performance in the fields of photocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), carbon dioxide reduction reaction (CO 2 RR), organic synthesis and pollutant degradation due to its unique structure, flexibility and resulting excellent photoelectric and catalytic properties. The stability problems caused by perovskite's susceptibility to environmental influences hinder its further application in the field of photocatalysis. Therefore, this paper innovatively summarizes and analyzes the existing methods and strategies to improve the stability of perovskite in the field of photocatalysis. Specifically, (i) component engineering, (ii) morphological control, (iii) hybridization and encapsulation are thought to improve the stability of perovskites while improving photocatalytic efficiency. Finally, the challenges and prospects of perovskite photocatalysts are discussed, which provides constructive thinking for the potential application of perovskite photocatalysts. [Display omitted] • Propose method of perovskites modification to combine high stability and efficiency. • Apply methods of improving the stability of perovskites in photocatalysis. • The challenges and prospects for more stable perovskite catalysts are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Co LDH/C, O co-doped g-C 3 N 4 2D/2D heterojunction has been first fabricated. • The modification of 2-methylimidazole enhanced photoconversion efficiency. • 2D/2D heterojunction exhibits excellent molecular oxygen activation. • The formed charge carrier transfer pathway promotes photoelectron transfer. • 2D/2D heterojunction possesses weakened surface charge carrier recombination. Molecular oxygen is a green and low-cost oxidant, which can be activated to produce reactive oxygen species by solar-light-driven photocatalysis. Here, Ni-Co LDH infused C, O co-doped g-C 3 N 4 two-dimensional (2D) ultrathin nanosheet was prepared by a simple thermal polymerization coupling hydrothermal method. The molecular oxygen activation was estimated by the quantitative determination of •O 2 − and 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation. 2D/2D heterojunction exhibits impressive photocatalytic performance. The arrestive activation efficiency is derived from the regulated energy band position, the broadened solar light absorption range, and the enhanced photoexcited electron transfer. Benefitting from these merits, the surface charge transfer efficiency of 2D/2D heterojunction is promoted to 51.3% from 14.3% (g-C 3 N 4). The surface recombination rate constant is reduced to 0.0011 s−1 from 0.0042 s−1 (g-C 3 N 4). The feasible photocatalytic mechanism for molecular oxygen activation is expounded based on experimental analysis. [ABSTRACT FROM AUTHOR]

• The characteristics of BP, h-BN, g-C 3 N 4 , graphene, and COFs are introduced. • The recent advances in element doping and heterojunction constructing are reviewed. • Organic amendment, hydroxyl modification, and dye sensitization are introduced. • The applications in HER, CO 2 RR, NRR, OER, and ORR are concluded. Semiconductor photocatalysis has been recognized as a feasible strategy for effective utilization of solar power to alleviate the energy shortage and environmental crisis. Efficient photocatalytic process over two dimensional (2D) ultrathin nanomaterial is one of the most paramount technologies for solving these problems. In this review, we begin with a brief introduction of five nonmetal-based 2D ultrathin nanomaterials (including black phosphorus (BP), hexagonal boron nitride (h-BN), covalent organic frameworks (COFs), graphene, and polymeric graphitic carbon nitride (g-C 3 N 4)), which mainly discusses the special characteristics of these materials. And then, as the main content of the article, recent advances of optimizing strategies for these five 2D materials are reviewed from the aspects of element doping and construction of heterojunction. We subsequently discuss the new strategies that may be effective for future optimization. Furthermore, the applications of nonmetal-based 2D photocatalysts in energy such as H 2 evolution, CO 2 reduction, N 2 fixation, O 2 evolution, and O 2 reduction are concluded. Finally, conclusions and outlooks are given for future potential directions. [ABSTRACT FROM AUTHOR]

• FeOOH QDs/CQDs/g-C 3 N 4 0D/2D heterojunction has been first prepared. • 0D/2D heterojunction can realize H 2 O 2 generation and in-situ decomposition. • The composite has excellent charge carrier transfer and separation efficiency. • The introduction of CQDs can improve the photoconversion efficiency. • The generated Fe2+ in FeOOH QDs can promote H 2 O 2 in-situ decomposition. Hydrogen peroxide (H 2 O 2) was generally considered as an ideal energy carrier and environment-friendly oxidant to process environmental modification. Here, FeOOH QDs and CQDs was interspersed on g-C 3 N 4 ultrathin nanosheet to promote H 2 O 2 generation and in-situ decomposition. FeOOH QDs/CQDs/g-C 3 N 4 composite (FCCN) exhibited excellent photoactivity for degrading oxytetracycline (OTC) under visible light illumination. The accelerated photoactivity is ascribed to the following merits: 1) the exciton dissociation interface and carrier transfer channel are fabricated to facilitate photoexcited electron transfer; 2) the photoexcited electron can be rapidly utilized by molecular oxygen to generate H 2 O 2 , resulting in facilitated molecular oxygen activation; 3) Fe3+ in FeOOH QDs is reduced to Fe2+ by photoexcited electron, and then reacts with generated H 2 O 2 to produce OH, thereby promoting photodegradation efficiency. The H 2 O 2 generation yield of FCCN-2 composite was 224.24 µmol h−1 g−1, which was higher than that of pure g-C 3 N 4. 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation and O 2 − quantitative determination displayed outstanding molecular oxygen activation capacity of hybrid composite. Moreover, 0D/2D heterojunction photocatalyst displayed weakened charge carrier recombination efficiency (0.0015 s−1) and expedited surface carrier transfer efficiency (41.01%) compared to g-C 3 N 4 and CQDs/g-C 3 N 4 photocatalyst. Finally, the photodegradation mechanism were rationally evaluated based on the experiment results. [ABSTRACT FROM AUTHOR]