Rational Construction of a 0D/1D S-Scheme CeO2/CdWO4 Heterojunction for Photocatalytic CO2 Reduction and H2 Production

Enhanced Photocatalytic Synthesis of Urea from co-Reduction of N2 and CO2 on Z-Schematic SrTiO3-FeS-CoWO4 Heterostructure

The photocatalytic co-reduction of CO2 and N2 is a sustainable method for urea synthesis under mild conditions. However, high-yield synthesis of urea is a challenge due to the sluggish kinetics of the C-N coupling reaction. Herein, we have successfully engineered a Z-scheme photocatalyst, SrTiO3-FeS-CoWO4, for boosting photocatalytic urea synthesis via enhancing the initial CO2 and N2 adsorption step and reducing the energy barrier for the C-N coupling reaction. A high urea yield of 8054.2 μg ⋅ gcat -1 ⋅ h-1 was achieved on SrTiO3-FeS-CoWO4, which was significantly higher than the state-of-the-art. The SrTiO3-FeS-CoWO4 Z-scheme photocatalyst, with accelerated charge transfer by FeS, not only had dual active sites for the chemical adsorption and activation of CO2 and N2, but also retained the high conduction band (-1.50 eV) and accelerated supply of electrons and protons, which are responsible for its good photoreduction activity and significantly reduced energy barrier for the rate-determining step of C-N coupling reaction.

Nanostructured CeO2 photocatalysts: optimizing surface chemistry, morphology, and visible-light absorption

Emerging photocatalytic applications of cerium dioxide (CeO2) include green hydrogen production, CO2 conversion to fuels, and environmental remediation of various toxic molecules. These applications leverage the oxygen storage capacity and tunable surface chemistry of CeO2 to photocatalyze the chosen reaction, but many open questions remain regarding the fundamental physics of photocatalysis over CeO2. The commonly ascribed 'bandgap' of CeO2 (∼3.1 eV) differs fundamentally from other photocatalytic oxides such as TiO2; UV light excites an electron from the CeO2 valence band into a 4f state, generating a polaron as the lattice distorts around the localized charge. Researchers often disregard the distinction between the 4f state and a traditional, delocalized conduction band, resulting in ambiguity regarding mechanisms of charge transfer and visible-light absorption. This review summarizes modern literature regarding CeO2 photocatalysis and discusses commonly reported photocatalytic reactions and visible light-sensitization strategies. We detail the often misunderstood fundamental physics of CeO2 photocatalysis and supplement previous work with original computational insights. The exceptional progress and remaining challenges of CeO2-based photocatalysts are highlighted, along with suggestions for further research directions based on the observed gaps in current understanding.

Ti3 C2 -modified g-C3 N4 /MoSe2 S-Scheme Heterojunction with Full-Spectrum Response for CO2 Photoreduction to CO and CH4

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-C3 N4 /Ti3 C2 /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 Ti3 C2 materials provides plentiful active sites for CO2 reaction, and its superior electrical conductivity is also favorable for the migration of photogenerated electrons.

Sputter -coated N-enriched mixed metal oxides (Ta2O5-Nb2O5-N) composite: A resilient solar driven photocatalyst for water purification

This study demonstrated the formation of N-enriched mixed metal oxides (Ta₂O₅-Nb₂O₅-N and Ta₂O₅-Nb₂O₅) thin film composites used as photocatalysts to degrade P-Rosaniline Hydrochloride (PRH-Dye) dye under solar radiation. By controlling the N gas flow rate during the sputtering process, the N concentration in the Ta₂O₅-Nb₂O₅-N composite is significantly included, and demonstrated by XPS and HRTEM analysis. With the help of XPS and HRTEM investigations, it was determined that the addition of N to Ta₂O₅-Nb₂O₅-N significantly enhances the active sites. The Ta-O-N bond (N 1 s and Ta 4p_3/2 spectra) was verified by the XPS spectra. Ta₂O₅-Nb₂O₅ was found to have a lattice interplanar distance (d-spacing) of 2.52, whereas Ta₂O₅-Nb₂O₅-N showed the 2.5 (620 planes). A sputter-coated Ta₂O₅-Nb₂O₅and Ta₂O₅-Nb₂O₅-N photocatalysts were prepared, and their photocatalytic activity was evaluated using PRH-Dye as a model pollutant under solar radiation by adding H₂O₂ (0.01 mol). The photocatalytic activity of the Ta₂O₅-Nb₂O₅-N composite was compared with TiO₂ (P-25) and Ta₂O₅-Nb₂O₅. Ta₂O₅-Nb₂O₅-N showed very high photocatalytic activity compared to Degussa P-25 TiO₂ and Ta₂O₅-Nb₂O₅ under solar radiation and confirmed the presence of N in Ta₂O₅-Nb₂O₅-N significantly increased the generation of ˙OH radicals (in pH 3, 7 and 9). With the use of LC/MS, the stable intermediates or metabolite created during the photooxidation of PRH-Dye were assessed. The results of this study will provide useful insights on how Ta₂O₅-Nb₂O₅-N influences the efficiency of water pollution remediation.