Stabilizing Rh nanoparticles using a TiO2 array with oxygen vacancies for high-performance pH-wide hydrogen evolution

Abstract

Active and durable catalysts are crucial for the hydrogen evolution reaction (HER). In the volcano plot, rhodium (Rh) and platinum (Pt) are positioned closely, while the activity and stability of Rh are much inferior to those of Pt. Here, we developed a Rh/TiO₂/Ti electrocatalyst to mitigate Pt dependency. The in situ formed TiO₂ with oxygen vacancies was prepared utilizing Ti foam as the Ti source. The TiO₂ support can confine Rh nanoparticles and ensure charge accumulation at the Rh site, while Rh can enhance the conductivity of TiO₂. DFT calculations demonstrate that the strong interaction between Rh and TiO₂ could regulate the electronic structure of Rh, thereby accelerating water dissociation and optimizing the adsorption strength of *H. Consequently, compared to Rh/Ti, Rh/TiO₂/Ti exhibits significantly enhanced HER activity, requiring overpotentials of only 37.3 and 34.3 mV to reach 10 mA cm⁻² in the alkaline and acidic HER, respectively. Furthermore, the vertical nanoarray structure, surface roughness, and metal–support interaction endow Rh/TiO₂/Ti with remarkable durability. It works in both alkaline and acidic media for 120 hours at 10 mA cm⁻² with unnoticeable activity decline, outperforming commercial Pt/C. This work provides a strategy to overcome the activity and stability limitations of Rh-based catalysts, providing references for promising catalysts for water electrolysis.