Phase-Dependent Synthesis of Ru Grown on TiO2 for Solar Driven H2 Evolution

Abstract

Crystal phase engineering provides a promising strategy for enhancing photocatalytic hydrogen evolution performance, yet the precise impact of phase structure on activity requires further exploration. In this study, hcp- and fcc-phase Ru nanoparticles were synthesized via precursor and solvent-controlled reduction processes and integrated with TiO₂. Photocatalytic hydrogen evolution tests reveal that hcp-Ru/TiO₂ achieves the highest H₂ production rate of 23.52 μmol/h, surpassing fcc-Ru/TiO₂ (11.18 μmol/h) and bare TiO₂ (4.72 μmol/h). Electrochemical and photophysical analyses demonstrate that hcp-Ru/TiO₂ exhibits superior charge separation and transfer efficiency, as evidenced by the lowest charge transfer resistance, highest photocurrent response, and prolonged fluorescence lifetime. Theoretical calculations further confirm that hcp-Ru offers optimal hydrogen adsorption energy (ΔG_H* = −0.14 eV), contributing to reduced overpotential and enhanced catalytic activity. This work underscores the critical role of Ru crystal phases in driving photocatalytic performance and provides new insights into phase engineering for sustainable energy applications.