p‐Cu(OH)₂/n‐SrTiO₃ Heterojunction for Efficient Photocatalytic Hydrogen Production

Abstract Improving the efficiency of well‐known photocatalysts in the hydrogen evolution reaction is contingent upon the development of cost‐effective and highly efficient co‐catalysts. The rapid recombination of photogenerated charges within semiconductor materials, such as SrTiO₃ (STO), results in reduced photocatalytic efficiency. To address this, copper‐based co‐catalysts have garnered considerable attention due to their relative low‐cost, natural abundance of constituents, and promising reactivity. In this work, p‐Cu(OH)₂/n‐SrTiO₃ heterojunctions are prepared for efficient photocatalytic hydrogen production. The SrTiO₃ photocatalysts with a flower‐like morphology decorated with Cu(OH)₂ at different weight percentages of Cu (0.1, 0.5, 1, 2, and 5 wt.%) are successfully prepared using a simple solvothermal and photodeposition process. The p‐Cu(OΗ)₂/n‐SrTiO₃ composite with 1 wt.% Cu content exhibits significant enhancement toward photocatalytic hydrogen production compared to the pristine STO, achieving a rate of ∼139 µmol h⁻¹ (∼6950 µmol g⁻¹ h⁻¹ mass activity) under λ > 360 nm light irradiation which is ≈3.5 times higher than that of single‐component STO. X‐ray photoelectron spectroscopic studies indicate formation of Cu(OH)₂ phase. Moreover, UV–vis/NIR, EIS spectroscopy, and photocatalytic evaluation studies indicate that the improved photocatalytic performance arises from the formation of p‐n junction at the Cu(OH)₂/STO interface that promotes enhanced charge carrier transfer and separation within the heterojunctions.