Work

Cu9S5/Gel-Derived TiO2 Composites for Efficient CO2 Adsorption and Conversion

Year: 2025

Type: article

Abstract: Engineering phase-selective gel composites presents a promising route to enhance both CO2 adsorption and conversion efficiency in photocatalytic systems. In this work, Cu9S5/TiO2 gel composites were synthesized via a hydrazine-hydrate-assisted hydrothermal method, using TiO2 derived from a microwave-assisted sol–gel process. The resulting materials exhibit a porous gel-derived morphology with highly dispersed Cu9S5 nanocrystals, as confirmed by XRD, TEM, and XPS analyses. These structural features promote abundant surface-active sites and interfacial contact, enabling efficient CO2 adsorption. Among all samples, the optimized 0.36Cu9S5/TiO2 composite achieved a methane production rate of 34 μmol·g−1·h−1, with 64.76% CH4 selectivity and 88.02% electron-based selectivity, significantly outperforming Cu9S8/TiO2 synthesized without hydrazine hydrate. This enhancement is attributed to the dual role of hydrazine: facilitating phase transformation from Cu9S8 to Cu9S5 and modulating the interfacial electronic environment to favor CO2 capture and activation. DFT calculations reveal that Cu9S5/TiO2 effectively lowers the energy barriers of critical intermediates (*COOH, *CO, and *CHO), enhancing both CO2 adsorption strength and subsequent conversion to methane. This work demonstrates a gel-derived composite strategy that couples efficient CO2 adsorption with selective photocatalytic reduction, offering new design principles for adsorption–conversion hybrid materials.

Source: Gels

DOI: 10.3390/gels11090711