Harnessing Light and CO₂ With Copper-Nickel on TiO₂ Photocatalysts for Methanol Production

The contemporary focus on global concerns such as carbon dioxide (CO₂) emissions impacting the environment and contributing to the energy crisis has prompted exploration into alternatives, with photocatalysis emerging as a potential solution. This research involved the development of a PT (TiO₂) photocatalyst, synthesized through the hydrothermal method and enhanced with double co-catalysts of copper and nickel via the wet impregnation technique. The characteristics of the resulting photocatalysts were comprehensively examined using various techniques, including XRD, Raman, UV-Vis DRS, surface area and pore analysis, SEM-EDX, HRTEM, XPS, PL, and EPR. The characterization outcomes revealed that the PT phase comprised anatase, brookite, and rutile. The incorporation of double co-catalysts was evident through the emergence of new peaks in the XRD diffraction pattern, corroborated by SEM, HRTEM, and XPS analysis. In the activity test, CNT-4 (Cu−Ni/TiO₂-400) exhibited the highest methanol yield at 772.41 μmole g⁻¹ h⁻¹, followed by CONTT-4 (CuO−NiTiO₃/TiO₂-400) with 750.38 μmole g⁻¹ h⁻¹ after three hours of irradiation using a 300 W xenon lamp, while methanol in PT formed only after three hours of irradiation. The presence of co-catalysts significantly influenced methanol yield, attributed to the increased active sites for the reaction and the reduced band gap, impacting light absorption optimization and suppressing electron-hole recombination. In CNT-4, the formation of Ti³⁺ associated with oxygen vacancies facilitated the generation of more products.