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Graphite carbon nitride (g‐C3N4), as a non‐metallic photocatalyst, possesses special band structure, excellent stability and unique surface properties, which has become a focus of attention for photocatalytic application. However, pure g‐C3N4 is subject to the limit of visible light response, small specific surface area and rapid recombination of photogenerated carriers, which leads to its low photocatalytic efficiency. Due to the unique electronic structure, various quantum dots (QDs) can be applied to modify g‐C3N4 to improve the photocatalytic activity. Thus, we highlight these QDs modified g‐C3N4‐based composites by emphasizing their synthesis, their physicochemical properties as well as their photocatalytic applications in CO2 reduction, hydrogen production and pollutants degradation in this review. At last, critical summaries and some perspectives on the challenges and directions in this research field are also presented. [ABSTRACT FROM AUTHOR]

The development of photocatalytic technology can not only reduce CO 2 emissions, but also realize the effective utilization of solar energy, thus alleviating the global energy crisis. In this work, BiOIO 3 /g-C 3 N 4 Z-scheme heterojunction modified by Ti 3 C 2 nanosheets was designed and fabricated through hydrothermal method and electrostatic self-assembly strategy. The g-C 3 N 4 /BiOIO 3 /Ti 3 C 2 (4 wt%) photocatalytic system exhibited the optimal photocatalytic efficiency, reaching 5.88 and 1.55 μ mol/g/h for CO and CH 4 , respectively, and the CO production rate was 6.6 folds as high as that of bare g-C 3 N 4. Various characterization techniques were utilized to research the physicochemical properties of as-prepared photocatalysts. Z-scheme heterojunction formed between g-C 3 N 4 and BiOIO 3 and the decorating of 2D Ti 3 C 2 co-catalyst were responsible for the boosted photocatalytic behavior. Z-scheme heterojunction could prevent the recombination of charge carriers, the co-catalyst Ti 3 C 2 acted as electron sink could achieve quick shift of photo-induced electrons and supply numerous active sites for photocatalytic reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Direct Z-scheme FeWO 4 /NiAl-LDH heterostructure was fabricated. • The 10%FWLDH possessed the optimal photocatalytic CO yield. • The effective separation of the light-induced e-/h+ pairs was available on FWLDH composite. In recent years, photocatalytic reduction of carbon dioxide technology has been considered as an effective approach to moderate the energy crisis. In order to achieve efficient reduction of CO 2 , direct Z-scheme heterostructure composed of NiAl-LDH flower-like sphere and FeWO 4 nanoflakes (FWLDH) were obtained through a facile hydrothermal strategy. The prepared FWLDH photocatalysts revealed outstanding performance for CO 2 photoreduction to CO under the irradiation of visible light. The 10%FWLDH possessed the optimal photocatalytic CO yield (5 μmol· g−1·h−1), reaching up to 2.4 folds higher than that of pristine LDH (2.1 μmol·g−1·h−1). In addition, the CO selectivity was more than 93% over hydrogen evolution from the side reaction of water reduction. Finally, EPR characterization indicated that the electron transfer mechanism of FWLDH catalyst conformed to the Z-scheme pattern. The effective separation of the light-induced electron-hole pairs and the enhancement of the photoelectron reduction ability at the NiAl-LDH conduction band were the reasons for the prominent improvement of the photocatalytic performance of NiAl-LDH. This research could provide a novel perspective for designing photocatalyst with high efficiency for CO 2 photoreduction. [ABSTRACT FROM AUTHOR]