Highly Stable and Active Ru Clusters Supported on Boron Carbon Nitride for Acidic Water Oxidation

Abstract

In recent years, metal oxides, such as IrO2, have been widely used in proton exchange membrane water electrolysis (PEMWE) because of their excellent catalytic activity and long-term stability [1]. However the high price and scarcity of these catalysts were not enough to meet the requirements of PEMWE [2]. Therefore, it is significant to explore novel electrochemically active, stable, and low-cost catalysts.In this paper, a uniformly dispersed Ru confined on boron carbon nitride support was synthesized and studied. The surface chemical states of Ru were tuned by the interaction between Ru and the active N in boron carbon nitrogen (BCN), forming a highly stable Ru-N bond. Benefiting from a graphene-like structure, the BCN-0.5Ru catalyst exhibited greater conductivity than RuO2. The strong interaction between Ru and the BCN support also allowed for accelerated charge transfer at the electrode interface.Transmission electron microscopy (TEM) investigations revealed that Ru clusters were uniformly dispersed on BCN (Figure 1a), and the particle size distributions (Figure 1b) showed that the Ru clusters possessed an average particle size of 4 nm. It suggests that the Ru nanoclusters on the BCN support had small particle sizes and a narrow particle size distribution. These results demonstrated that the BCN support helped disperse the Ru metal nanoclusters more homogeneously than what occurred when RuO2 was prepared via direct RuCl3 annealing. The electrochemical performance of oxygen evolution reaction (OER) for BCN-xRu catalysts in O2-saturated 0.5 M H2SO4 solution was evaluated. The BCN-0.5Ru catalyst demonstrates a low overpotential of 164 mV at a current density of 10 mA cm–2 and remains stable for 12 h in acidic electrolyte (Figure 1c). In contrast, RuO2 without any support fails in only 1 h (Figure 1c). We propose that the surface chemical states of Ru supported by BCN may play an important role in enhancing stability. This study provides insights into designing and synthesizing high-performance electrocatalysts for acidic OER.