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The preparation of heterojunction photocatalysts with staggered energy band structures and proper interfacial contacts is an effective way to improve CO 2 conversion. This study adopted a simple hydrothermal method to form Cu 2 O on the surface of BiOBr, and s scheme BiOBr/Cu 2 O heterojunctions with close contacts were constructed. The rate of CO 2 reduction over the catalyst was tested in a gas-solid reactor simulating sunlight. The results show that the BiOBr/Cu 2 O composite moderately yields CH 4 with an efficiency of 22.78 μmol g−1h−1 for conversion from CO 2 to CH 4 in visible light, while pure BiOBr yields only CO. In addition, Transient photocurrent response, Electrochemical impedance spectroscopy, and Photoluminescence measurements demonstrated that the BiOBr/Cu 2 O had a strong photogenerated carrier transfer and separation and high photo-availability, while key intermediates favoring CH 4 yield were found by in situ IR. Finally, the possible photocatalytic mechanism was explored based on the energy band structures of BiOBr and Cu 2 O in the characterization. [Display omitted] • BiOBr/Cu 2 O with S-scheme heterostructure was synthesized using a simple approach. • Cu 2 O as an active site adjusting the photoreduction of CO 2 to CH 4. • Possible photocatalytic reaction mechanism for CO 2 reduction by 20%-BiOBr/Cu 2 O proposed. [ABSTRACT FROM AUTHOR]

Designing S-scheme heterojunctions is an effective method to improve the charge localization on the surface of photocatalysts. Their effective charge transport routes can be enhanced with the help of interfacial noble metal nanoparticles. Herein, an Ag/CuO@ZnIn 2 S 4 plasma S-scheme heterojunction with heterogeneous interfacial covalent bonds was successfully designed. The 15% Ag/CuO@ZnIn 2 S 4 has promising photocatalytic performance and stability with the highest CO and CH 4 yields of 6.9 and 54.4 µmol g−1 h−1 and CH 4 selectivity of 92.8%. It is evidenced that the photogenerated charge can be efficiently separated and transported due to the influence of both the S-scheme electron migration mode and the Cu-S covalent bond. The process is further accelerated by using precious metals as cocatalysts, which can then selectively convert CO 2 into CH 4. This research is expected to provide helpful information for engineering S-scheme heterojunction photocatalysts and investigating their charge transfer kinetics. [Display omitted] • Design of a S-scheme heterojunction to promote the separation of carriers. • Built the Cu-S bonds to accelerate the transfer of charges. • Utilizing the LSPR effect to generate hot electrons and enhance light absorption. • The Ag/CuO@ZnIn 2 S 4 photocatalysts can selectively reduce CO 2 to CH 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dual-plasma enhanced g-C 3 N 4 /Pd/MoO 3-x heterojunction was fabricated for high-selectivity photocatalytic CO 2 reduction. • The g-C 3 N 4 /Pd/MoO 3-x composites revealed excellent near-infrared absorption ability. • The carrier separation efficiency was effectively improved under the synergistic effect of MoO 3-x and Pd nanosheets. • The g-C 3 N 4 /Pd/MoO 3-x S-scheme heterojunction displayed high photocatalytic performance and CO selectivity. • The S-scheme charge transfer mechanism was proposed based on UPS and ESR results. The localized surface plasmon resonance (LSPR) effect has shown significant progress in enhancing the efficiency of light absorption and separating photogenerated carriers. Herein, the dual-plasma enhanced 2D/2D/2D g-C 3 N 4 /Pd/MoO 3-x (CPM) S-scheme heterojunction photocatalysts were synthesized using the method of hydrothermal and electrostatic self-assembly for high-selectivity photocatalytic reduction of CO 2 to produce CO. The dual LSPR effect of MoO 3-x and ultrathin Pd nanosheets synergistically broadened the optical response range of the CPM composites and successfully improved the photocatalytic activity and near-infrared (NIR) performance. The optimized CPM-30 photocatalysts exhibited CO yields of 18.55 μmol g−1 with a selectivity of 96.3%. In addition, the CO yield reached 3.92 μmol g−1 after 4 h of NIR light photoirradiation. The electron spin resonance (ESR) and ultraviolet photoelectron spectroscopy (UPS) tests showed that the S-scheme heterojunctions were constructed by coupling g-C 3 N 4 /Pd nanosheets and MoO 3-x. This work will provide a reference for improving product selectivity through the design of two-dimensional composites and the utilization of plasma materials. [ABSTRACT FROM AUTHOR]

S-scheme heterojunction of In 2 O 3 /H 1.5 CN/2Au was prepared by hydrothermal, acidizing and calcination methods. The two-dimensional thin layer H 1.5 CN avoided the aggregation of In 2 O 3 and completed the S-scheme charge transfer with In 2 O 3. Moreover, Au not only enhanced the visible light absorption capacity of composites but also provided more active sites for CO 2 reduction. [Display omitted] • S-scheme heterojunction of In 2 O 3 /H 1.5 CN/2Au achieve CO 2 photocatalytic conversion to CO and CH 4. • The enhanced photocatalytic activity results from effective interfacial charge migration and separation and increased active sites. • The LSPR effect of Au improves the utilization of visible light. The construction of S-scheme heterojunction is of great significance for the photocatalytic reduction of CO 2. Here, we prepared two-dimensional (2D) ultra-thin g-C 3 N 4 by acidifying the carbon nitride precursor, and used In 2 O 3 to construct a S-scheme heterojunction with 2D g-C 3 N 4 , and finally In 2 O 3 /H 1.5 CN was modified with Au nanoparticles. The physicochemical properties of the prepared materials were studied by SEM/TEM, XPS, DRS, PL and photochemical test. Meantime, the S-scheme charge transfer mechanism was demonstrated by UPS and ESR. As a result, on the one hand, S-scheme heterojunction accelerated the transfer of electrons on the CB of In 2 O 3 to the VB of g-C 3 N 4 , avoided the recombination of photon-generated carrier. On the other hand, Au, as an effective cocatalyst, promoted photoinduced electron transfer and provided more active sites for CO 2 reduction and the local surface plasmon resonance phenomenon caused by Au NPs enhanced the visible light absorption capacity of the composite material. Moreover, 2D thin layer of g-C 3 N 4 played a carrier effect to disperse In 2 O 3 cube. Therefore, In 2 O 3 /H 1.5 CN/2Au had stable CO 2 reduction products, and the yields of CO/CH 4 reached 141.24/77.05 μmol/g. [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]