Capping strategy for electrocatalysts with ultra-low platinum metal loading

The urgent demand for terawatt-scale clean energy necessitates the rational design of noble metal catalysts with minimal noble metal loading while maintaining high catalytic activity. However, the durability of low-loading catalysts is a critical concern for their successful industrial implementation. Here, we present a capping strategy using an amorphous HfO₂ (m-HfO₂) to address this issue. Take Pt/C catalysts with Pt loading as low as 81.39 ng cm⁻² as an example, we demonstrate that the m-HfO₂ layer (10 nm) serves as an efficient mass transport channel for underneath Pt active sites, and effectively mitigates bubble-induced blockage of active sites by separating bubble formation sites with Pt active sites. Thus, the resulting catalyst exhibits a remarkable mass activity of 122.87 A mg⁻¹ and an overpotential of 11 mV at 10 mA cm⁻². Furthermore, the m-HfO₂ plays a crucial role in eliminating the structural transformation and extending the lifetime of Pt-based catalysts, as evidenced by no loss of specific activity after consecutively cycling the catalyst for over 100 h. Such a capping strategy is potentially applied to other types of reactions and catalyst systems.