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Improved photogenerated carrier separation efficiency is of importance for improving photocatalytic activity. Herein, the photocatalytic CO2 reduction of a 3D/0D ZnIn2S4/NiS ohmic‐junction photocatalyst under simulated sunlight is studied. The ZnIn2S4–2%NiS sample has the best excellent photoreduction CO2 performance facilitated by triethanolamine (TEOA) reagents, the ZnIn2S4–2%NiS sample with a CO yield of 12.63 μmol g−1 h−1, which is two times that for pure ZnIn2S4 (6.37 μmol g−1 h−1). It is demonstrated that NiS nanoparticles not only improve the efficiency of electron generation and charge separation by constructing a tight contact ohmic‐junction, but also act as a cocatalyst to extend the photoreaction range and lower the reaction barrier, which effectively accelerates the photocatalytic reduction reaction. Additionally, the 3D structure of ZnIn2S4 has an excellent specific surface area that facilitates the dispersion of NiS. The generation, separation, and migration of photogenerated electron holes are studied from the kinetics perspective through transient photocurrent response, linear sweep voltammetry curve and photoluminescence spectroscopy. In situ Fourier transform infrared spectroscopy is applied to study the CO2 photoreduction process. Herein, the important role of cocatalyst and ohmic‐junction in improving photocatalytic activity is revealed and a new idea for the construction of efficient photocatalysts is provided. [ABSTRACT FROM AUTHOR]

Wide-light absorption performance and efficient carrier separation ability are the necessary conditions for excellent photocatalytic materials. In this research, g-C 3 N 4 QDs (CN QDs) and Au nano-particles (NPs) co-modified CeO 2 /Fe 3 O 4 micro-flowers (MFs) photocatalyst (CACeF) has been prepared. CO 2 photoreduction experiments showed that the composite had obviously enhanced photoreduction activity and photocatalytic stability. The yields of CO and CH 4 over it as catalyst in 4 h is about 5 and 8 times greater than that of pure CeO 2. Photoelectrochemical tests showed that the heterojunction between CN QDs and Au NPs can greatly improve the carrier separation ability and the light-utilization efficiency of photocatalysts. Besides, the excellent electronic transmission performance of Au NPs provided a specific channel for the electron transmission, and the strong local surface plasmon resonance (LSPR) of Au NPs resulted in a lot of hot-electrons can directly take part in the CO 2 photoreduction. The synergistic effect between CN QDs and Au NPs can further enhance the photocatalytic activity of the photocatalyst. Fe 3 O 4 QDs can ensure the effective recovery and reuse of the composite without affecting the photocatalytic performance of composite. Finally, a potential photoreduction mechanism of CN QDs and Au NPs co-modified CeO 2 /Fe 3 O 4 MFs photocatalyst were discussed in total. [Display omitted] • g-C3N4 QDs/Au NPs/CeO2/Fe3O4 has been prepared for the CO2 photoreduction. • Light-absorption performance of photocatalyst has been greatly enhanced. • Au efficiently speeds up the electrons' generation efficiency in semiconductors. • Synergistic effect of CN QDs/Au NPs enhanced the photoreduction performance. • Fe3O4 QDs can ensure the recovery without affecting the photocatalytic performance. [ABSTRACT FROM AUTHOR]

rGO modified g-C 3 N 4 /R-CeO 2 Multi-interface contact S-scheme heterojunction photocatalyst maximizes the transfer efficiency of photogenerated electron and the CO 2 adsorption ability, thus greatly improving the CO 2 photoreduction performance. [Display omitted] • 2D-1D-2D g-C 3 N 4 /R-CeO 2 /rGO photocatalyst has been prepared for CO 2 photoreduction. • 2D-1D-2D multi-interface contact structure is of help for carrier transfer process. • π-π conjugation effect and Ce4+/Ce3+ transformation facilitate electron transmission. • In-situ FTIR and 13C isotope tracer tests analysis the CO 2 photoreduction mechanism. Construction of multi-interface contact step-scheme (S-scheme) photocatalyst is a promising pathway to achieve high-electron transfer efficiency for photocatalytic CO 2 reduction. In this paper, g-C 3 N 4 nanosheets were selected as the main photocatalyst, rod-like CeO 2 (R-CeO 2) with unique Ce4+→Ce3+ conversion property and rGO were loaded on the g-C 3 N 4 surface to construct 2D-1D-2D sandwich photocatalyst. The yields of CO and CH 4 were about 63.18 and 32.67 μmol/g after 4 h when the rGO/R-CeO 2 /g-C 3 N 4 was used as catalyst, which were about 4 and 6 times higher than that of pure CN, respectively. Cyclic experiments proved that the composite had excellent photocatalytic and material stability. Photoelectrochemical tests showed that the construction of S-scheme electron transfer model and the introduction of rGO can great enhance the electron transmission and separation of photogenerated electron-hole pairs. CO 2 adsorption test identified that the loading of R-CeO 2 and rGO obviously enhanced the CO 2 adsorption ability of pure g-C 3 N 4. Density functional theory (DFT) calculations used to analyze the electron transfer path and the formation of the build-in electric field at the semiconductor interface. In-situ FTIR and 13CO 2 element-tracer detection carried out to research the process of CO 2 photoreduction. A possible multi-interface contact S-scheme electron transfer mechanism for enhanced CO 2 photoreduction activity has been discussed. [ABSTRACT FROM AUTHOR]

Pt@CeO 2 /3DCN heterojunction are prepared by calcination method and photoreduction technology. The enhanced photoreduction of CO 2 performance can be ascribed to the synergistic effects of the oxygen vacancies in CeO 2 for CO 2 activation and heterojunction for electron separation. Besides, Pt nanoparticles (NPs) on CeO 2 /3DCN can further promote the transfer of electrons, resulting in higher photocatalytic activity. • The Pt@CeO 2 /3DCN photocatalyst was successfully synthesized. • Pt@45CeO 2 /3DCN exhibit best ability of CO 2 photoreduction under UV light. • The synergy of CeO 2 and 3DCN improves the photocatalytic performance. The conversion of CO 2 into high value-added carbon-based compounds through photocatalytic reduction technology is considered as one of the more promising strategies to solve the greenhouse effect. And construction of heterojunction photocatalysts can promote the separation of photoelectron-hole pairs, so as to achieve higher activity of photocatalytic CO 2 reduction. Hence, Pt@CeO 2 /3DCN heterojunction are prepared by calcination method and photoreduction technology. The photocatalytic results revealed that Pt@CeO 2 /3DCN show better photocatalytic activity for reducing CO 2 into CO and CH 4 , compared with 3DCN. Especially, Pt@45CeO 2 /3DCN shows the maximum photocatalytic activity of 4.69 and 3.03 μmol·h−1·g−1 for CO and CH 4 under UV light irradiation, respectively, and the reduction activity did not decrease significantly after five cycles. The enhanced photoreduction of CO 2 performance can be ascribed to the synergistic effects of the oxygen vacancies in CeO 2 for CO 2 activation and heterojunction for electron separation. Besides, Pt nanoparticles (NPs) on CeO 2 /3DCN can further promote the transfer of electrons, resulting in higher photocatalytic activity. [ABSTRACT FROM AUTHOR]