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In this research, a ternary Cu-CuTCPP/Cu2O/CoAl-LDH composite with a dual Z-scheme heterostructure was fabricated based on a Cu2O photocatalyst and applied in photocatalytic CO2 reduction. The physicochemical properties of the prepared catalysts and the possible reaction mechanism in CO2 reduction were analyzed and studied by various characterization methods. The activity of CO2 reduction significantly increased, especially forming C2 products. The optimal yield of C2H4 and C2H6 reached 1.56 and 1.92 μmol g−1 h−1 respectively, which was 14.45 and 17.45 times that from using the Cu2O monomer. In addition, the selectivity of C2 products reached 37.4%. The satisfactory C2 yield was mainly due to the fact that Cu1+δ2(COO)3 nodes in Cu-CuTCPP contained adjacent Cu sites, which effectively promoted the C–C coupling reaction. Moreover, the dual Z-scheme heterojunction stimulated the separation of photogenerated electron–hole pairs and diminished the recombination rate. This work contributes to the development of novel photocatalysts with a dual Z-scheme heterojunction and facilitates the generation of valuable C2 products. [ABSTRACT FROM AUTHOR]

Energy shortage and global warming caused by the extensive use of fossil fuels are urgent problems to be solved at present. Photoreduction of CO2 is considered to be a feasible solution. The ternary composite catalyst g‐C3N4/Ti3C2/MoSe2 was synthesized by hydrothermal method, and its physical and chemical properties were studied by an array of characterization and tests. In addition, the photocatalytic performance of this series of catalysts under full spectrum irradiation was also tested. It is found that the CTM‐5 sample has the best photocatalytic activity, and the yields of CO and CH4 are 29.87 and 17.94 μmol g−1 h−1, respectively. This can be ascribed to the favorable optical absorption performance of the composite catalyst in the full spectrum and the establishment of S‐scheme charge transfer channel. The formation of heterojunctions can effectively promote charge transfer. The addition of Ti3C2 materials provides plentiful active sites for CO2 reaction, and its superior electrical conductivity is also favorable for the migration of photogenerated electrons. [ABSTRACT FROM AUTHOR]

The photocatalytic reduction of CO2 to hydrocarbons is expected to simultaneously alleviate the energy crisis and greenhouse effect. Herein, the ternary BiOCl/C/Cu2O catalysts with different mass ratios were compounded using a simple hydrothermal method, revealing better photocatalytic activity than the monomer. In the absence of sacrificial agents and photosensitizers, 25% BiOCl/C/Cu2O showed optimal photocatalytic performance. The CO and CH4 yields over 25% BiOCl/C/Cu2O reached 26.77 and 9.86 μmol g−1 h−1, which is 2.9 and 8.7 times higher than that of the pristine Cu2O, respectively. The ameliorative activity can be attributed to the construction of the Z-scheme heterostructure and carbon layer, which are conducive to the transfer and separation of photogenerated carriers. This study offers valuable references for the design and investigation of a Z-scheme heterojunction using a carbon layer as an electron transfer medium. [ABSTRACT FROM AUTHOR]

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 Eu-doped TiO 2 nanoparticles were successfully prepared by a simple sol-gel method. The properties of the catalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), N 2 adsorption-desorption, UV–vis diffuse reflectance and photoluminescence (PL) spectroscopy. The results indicated that Eu-TiO 2 catalysts had a high specific surface area, enhanced visible light response and low recombination rate of electron-hole pairs. The photocatalytic performances of Eu-TiO 2 catalysts for CO 2 reduction were investigated under 9 h irradiation of a 300 W Xe arc lamp. The maximum yields of CH 4 and CO over the optimized Eu-TiO 2 catalyst were 65.53 μmol/g.cat and 42.91 μmol /g.cat, respectively, which were approximately 13 times and 1 times higher than that of pure TiO 2 . The enhanced photocatalytic performance could be ascribed to the high-efficiency separation of photo-generated electron-hole pairs. [ABSTRACT FROM AUTHOR]

Photocatalytic reduction of CO 2 into hydrocarbon fuels, utilizing inexhaustible solar energy to simulate natural photosynthesis, is a promising approach to simultaneously alleviate environmental issues and energy crises. Among the developed photocatalysts, bismuth (Bi)-based materials have been extensively applied for photocatalytic CO 2 reduction due to their unique electronic configuration and excellent physicochemical properties. Various approaches have been investigated to enhance the photocatalytic performance of Bi-based photocatalysts for CO 2 reduction, among which constructing direct or indirect Z-scheme by coupling Bi-based materials with matching semiconductors is an effective method. In this review, the latest major advancements in the design of high-efficient Bi-based Z-scheme photocatalysts for photocatalytic CO 2 reduction are summarized, including structural engineering strategies for direct Z-scheme and several patterns of indirect Z-scheme construction. Moreover, the proposed S-scheme structure based on the Z-scheme structure is also briefly discussed. Finally, the current challenges and prospects of the future development of the Bi-based Z-scheme structure for CO 2 photoreduction are also presented and discussed. [Display omitted] • The progress on photocatalytic CO 2 reduction over Bi-based Z-scheme photocatalysts are summarized. • The relationship between Bi-based Z-scheme structure and the photocatalytic CO2 reduction activity was investigated. • The future development of the Bi-based Z-scheme structure for CO 2 photoreduction is discussed. [ABSTRACT FROM AUTHOR]

In this study, Er3+/Yb3+ co-doped NiAl-LDH (LDH:Er3+,Yb3+) photocatalysts were successfully fabricated through a solvothermal process. The results revealed that the LDH:Er3+,Yb3+ displayed promoted photoreduction CO 2 activity under Vis/NIR light irradiation. A maximum CO yield of 13.2 μmolg−1h−1 had been obtained on LDH:1%Er,2%Yb, which was 9.4 and 1.5 times higher as high as the pure LDH and the LDH:1%Er, respectively. The improved photocatalytic activity can be ascribed to the expanded photoresponse range to NIR light region caused by the upconversion effect of Er3+/Yb3+, and the improved photogenerated charge separation efficiency with Er3+/Yb3+ serving as an electron trap. The NIR photocatalytic activity and the improved light absorption of LDH: Er3+,Yb3+ indicate that the upconversion mechanism is involved in the whole photocatalytic process. Therefore, this result presents new insights for the rational construction of Vis-NIR light-driven photocatalysts with high-efficient solar energy utilization and practical application prospects in the future. • LDH:Er3+;Yb3+ was prepared via a solvothermal method. • The photocatalyst exhibited enhanced visible and NIR photoreduction activity. • The mechanism of Vis/NIR photocatalytic reaction on LDH:Er3+;Yb3+ was proposed. [ABSTRACT FROM AUTHOR]

• S-scheme Bi-BiOCl/MgIn 2 S 4 marigold microflower heterostructure. • 6 % Bi-BiOCl/MgIn 2 S 4 sample behaved the optimal photocatalytic performance for CO 2 photoreduction into CH 4. • Metal Bi acted as the bridge connecting the BiOCl and MgIn 2 S 4 to facilitate the charge transfer. Step-scheme (S-scheme) Bi-BiOCl/MgIn 2 S 4 heterostructure (BBOC/MIS) was successfully fabricated via NaBH 4 reduction and facile in-situ hydrothermal process and applied in photocatalytic CO 2 reduction. A part of BBOC ultrathin nanosheets processed by ultrasonication exfoliation was grown on the surfaces of MIS marigold microflower. Another part of BBOC and MIS exhibited as the core and shell of BBOC/MIS, respectively. The morphology, band alignment, optical and electronic characteristics of photocatalysts were comprehensively studied via diverse characterization methods. The S-scheme BBOC/MIS heterojunction possessed superior photocatalytic performance and well reusability to primarily convert CO 2 into CH 4 with high efficiency under the simulated solar light irradiation without using any sacrificial agent in water. Experimental results displayed that the 6% BBOC/MIS sample behaved the optimal photocatalytic performance in photocatalytic reduction of CO 2 , and its maximum CH 4 production rate could reach up to 4.29 μmol g−1 h−1, which was about 7.56 times as high as that of unadulterated MIS. The enhanced photocatalytic performance of BBOC/MIS could be attributed to the improved visible light response and highly-efficient separation of the photogenerated electron-hole pairs between BBOC and MIS through the S-scheme heterojunction interface. In addition, the metal Bi acted as the bridge connecting the BOC and MIS to facilitate the charge transfer, which greatly promoted the CO 2 photocatalytic reduction to CH 4. [ABSTRACT FROM AUTHOR]

• 20 % BiO 2- x/g-C 3 N 4 composites exhibited the best photocatalytic activity. • BiO 2-x narrowed the band gap and expanded the visible light range. • The separation and migration of photogenerated carriers are promoted. Photoreduction CO 2 to hydrocarbons are the sustainable and green methods to solve energy shortages and environmental pollution problems. Therefore, the development of efficient and environment-friendly photocatalysts remains a huge challenge, while coupling co-catalyst on traditional photocatalysts is a potential approach for improving photocatalytic activity. Here, a novel BiO 2-x co-catalyst coupled g-C 3 N 4 photocatalyst was prepared by a simple hydrothermal approach for the photocatalytic reduction of CO 2. The experimental results proved that BiO 2-x /g-C 3 N 4 composites played a vital part for promoting the photocatalytic capability. The 20 % BiO 2-x /g-C 3 N 4 composites exhibited the best photocatalytic capability under the simulated visible-light. A maximum yield of CO (42.29 μmol/gcat) and CH 4 (7.2 μmol/gcat) were obtained, which were 3.8 and 2.5 times that over pure g-C 3 N 4 , and its apparent quantum yield (AQY) was 1.5 % at 420 nm. According to the characterization results, the significantly increased photocatalytic activity could be ascribed to larger specific surface area, stronger visible-light absorption properties and more effective separation and transfer of photogenerated electron-hole pairs. Our finding provides a certain reference for the development and application of novel co-catalyst. [ABSTRACT FROM AUTHOR]

The photocatalytic reduction of CO2 to hydrocarbons is expected to simultaneously alleviate the energy crisis and greenhouse effect. Herein, the ternary BiOCl/C/Cu2O catalysts with different mass ratios were compounded using a simple hydrothermal method, revealing better photocatalytic activity than the monomer. In the absence of sacrificial agents and photosensitizers, 25% BiOCl/C/Cu2O showed optimal photocatalytic performance. The CO and CH4 yields over 25% BiOCl/C/Cu2O reached 26.77 and 9.86 μmol g−1 h−1, which is 2.9 and 8.7 times higher than that of the pristine Cu2O, respectively. The ameliorative activity can be attributed to the construction of the Z-scheme heterostructure and carbon layer, which are conducive to the transfer and separation of photogenerated carriers. This study offers valuable references for the design and investigation of a Z-scheme heterojunction using a carbon layer as an electron transfer medium. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalytic reduction of CO 2 to high-energy products is an effective way to utilize solar energy and mitigate the greenhouse effect. In this paper, a series of CQDs/Bi 12 O 17 Cl 2 /NiAl-LDH (C/BOC/LDH) photocatalysts were prepared via a one-pot hydrothermal method, demonstrated excellent photocatalytic CO 2 reduction performance. In the case of only water without any photosensitizer and sacrificial agent, the CO production rate on C/0.3BOC/LDH reached 16.4 μmol·g-1h−1, which is 6.7 times higher than that of the original LDH. The construction of Z-scheme heterojunctions inhibited the recombination of electrons with holes. The unique up-conversion PL behavior of CQDs benefitted the absorption of energy in the NIR by the photocatalyst. This study provides meaningful assistance for the design and construction of a ternary photocatalytic system with Z-scheme heterojunction and carbon-based co-catalyst. [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]

A series of flaked Mg/g-C 3 N 4 catalysts were synthesized via an in-situ hydrothermal deposition method and measured their photocatalytic activity for CO 2 reduction. The characterization results indicated that the obtained Mg/pCN catalysts had high surface area and massive active sites for CO 2 absorption. The introduction of Mg species had a positive effect to extend the spectral response property and increased the separation rate of photogenerated electron-holes pairs. Mg-doped g-C 3 N 4 catalysts showed much higher photocatalytic performance than pCN. The maximum CH 4 and CO yields of 17.09 and 4.13 μmol/g-cat, respectively, had been obtained for CO 2 reduction after 6 h reaction. [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]