Engineering Stable Cu-Doped SrTiO₃ Perovskites for Enhanced Photocatalytic CO₂ Reduction

Photocatalytic CO₂ reduction presents a sustainable pathway for renewable energy generation while addressing critical environmental challenges. Strontium titanate (SrTiO₃) has emerged as a highly efficient wide-bandgap semiconductor photocatalyst for CO₂ reduction. In this study, we investigate copper-doped strontium titanate (Cu/STO), synthesized via a hydrothermal method, which exhibits a well-defined cubic-like structure. The work focuses on optimizing the CO₂ reduction process by systematically varying the pH of the reaction medium using HCl and NaOH. Our findings reveal that pH significantly influences product selectivity, with a notable shift from methane (CH₄) to carbon monoxide (CO) production, highlighting the role of pH in modulating reaction pathways and product distribution. The introduction of pH control substances (such as HCl and NaOH) and their side products can influence selectivity by promoting undesired side reactions. Remarkably, the 2Cu/STO photocatalyst demonstrated exceptional structural stability across all tested pH conditions and maintained a highly stable morphology under neutral (uncontrolled) pH. This study introduces a novel strategy for designing stable and high-performance photocatalysts, emphasizing the critical role of pH control in enhancing both the stability and the efficiency of the photocatalytic CO₂ reduction process. These insights pave the way for advancing sustainable energy solutions through tailored photocatalytic systems.