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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]

Facilitating the separation of photoexcited electron-hole pairs and enhancing the migration of photogenerated carriers are essential in photocatalytic reaction. CoS/g-C 3 N 4 /NiS ternary photocatalyst was prepared by hydrothermal and physical stirring methods. The optimized ternary composite achieved a hydrogen yield of 1.93 mmol g−1 h−1, 12.8 times that of bare g-C 3 N 4 , with an AQE of 16.4% at 420 nm. The enhanced photocatalytic activity of CoS/g-C 3 N 4 /NiS was mainly ascribed to the synergistic interaction between the Z-scheme heterojunction constructed by CoS and g-C 3 N 4 and the NiS co-catalyst featuring a large amount of hydrogen precipitation sites, which realized the efficient separation and migration of photogenerated carriers. In addition, the CoS/g-C 3 N 4 /NiS heterojunction-co-catalyst system exhibited excellent photocatalytic stability and recyclability. • CoS/g-C 3 N 4 /NiS ternary photocatalyst was prepared by hydrothermal and physical stirring methods. • A large amount of hydrogen precipitation sites are available on CoS/g-C 3 N 4 /NiS ternary photocatalyst. • The Z-scheme heterojunction combined with the co-catalyst promoted the separation and migration of photogenerated carriers. [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]