Realizing CO2 reduction with H2O oxidation on g-C3N4-based photocatalysts is quite promising yet challenging. Herein, an efficient direct Z-scheme heterostructure of ultrathin CsPbBr3/g-C3N4 nanosheets is fabricated via a simple electrostatic self-assembly process, resulting in an effective photocatalytic reduction of CO2 to CH4 (184.0 μmol g−1) and CO (105.2 μmol g−1) with oxidation of H2O under AM 1.5G irradiation. Notably, in situ X-ray photoelectron spectroscopy (XPS) analysis demonstrated that a direct Z-scheme charge transfer mechanism at the CsPbBr3 and g-C3N4 interface is enabled, thereby achieving efficient charge separation and high redox potentials to drive photocatalytic CO2 reduction and H2O oxidation synchronously. Isotopic labelling experiments revealed that the adsorbed water is activated to release H atoms and eventually assists the CO2 reduction. Theoretical calculations further revealed that the p orbitals of Pb atoms hybridize with the 2π* orbitals of CO2 molecules, strengthening the affinity of CO2 and weakening the binding strength. Moreover, overlapping between Pb p orbitals and 5σ orbitals of CO molecules promote the protonation of CO* intermediates. This work provides an in-depth understanding and guidance for constructing high-efficiency catalysts for CO2 reduction with H2O oxidation.
Lang Pei,Haichuan Feng,Qinan Mao,Lixiang Wang,Yu Zhang,Xin Wen,Xusheng Wang,Xiao Liu
Efficient photocatalytic CO₂ reduction necessitates optimal charge balance and proton migration between the CO₂ reduction and H₂O oxidation half-reactions. However, traditional research has predominantly focused on optimizing these half-reactions independently, neglecting potential synergistic effects. Here, this work demonstrates a photothermal catalyst of Pt/Ta2O5-x nanoplates that synergistically leverages the photothermal effect and redox dual-site cooperation to simultaneously accelerate the CO₂ reduction and H₂O oxidation, thereby maximizing proton-electron transfer. The integration of photothermal effect and photocatalysis ensures a strong driving force for CO2 conversion while accelerating proton migration, with Pt plasmonics generating localized heat from solar energy. In-situ characterizations reveal that O vacancy in Ta2O5-x enhances H2O dissociation to provide abundant protons, while Pt acts as electron acceptor sites, effectively activating the C=O bond. Theoretical calculations further illustrate the synergistic CO2 reduction and H2O oxidation on Pt and O vacancy sites, where the oxidation of *OH to *OOH is synchronized with the *CO desorption to CO, significantly lowering the energy barrier for proton-coupled electron transfer. Impressively, the Pt/Ta2O5-x exhibits exceptional photothermal catalytic performance in CO2-to-syngas conversion with a syngas yield up to 1.97 mmol g⁻¹ h⁻¹, which is 16.3-fold higher than Ta2O5-x. Furthermore, the apparent quantum efficiency reaches 3.5% at 365 nm, and the syngas selectivity is a remarkable 82%, while also exhibiting good stability.
Photocatalytic reduction of CO 2 with H 2 O into CH 4 is a promising way to realize solar energy utilization and CO 2 conversion, in which the key issue is how to enhance and couple CO 2 reduction as well as H 2 O oxidation. In this work, we precisely fabricated a binary functional photocatalyst by loading Au@Pd nanoparticles onto V O -rich TiO 2 through a surfactant-free deposition-reduction method, whose fine structure was confirmed by aberration-corrected HAADF-STEM, EELS, EPR and XPS. Combining photocatalytic performance with a series of in situ FTIR measurements, we clarified the role of metallic sites and semiconductor support in coupling CO 2 reduction and H 2 O oxidation. Specifically, H 2 O oxidation process was facilitated by the V O -rich TiO 2 to contribute more protons, followed by the activation of CO 2 and protons primarily by the metallic Au@Pd sites to form the surface bounded Au@Pd-CO 2 − and Au@Pd-H species. By adjusting the ratio of Au@Pd nanoparticles and V O concentration to manipulate the Au@Pd-CO 2 − /Au@Pd-H ratio, CH 4 yield of 26.32 μmol/(g·h) and selectivity of electron toward CH 4 of 96% can be observed with minimal concomitant H 2 generation. These findings could open a feasible and universal route to enhance the photocatalytic efficiency of CO 2 conversion.
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