Enhancing the oxygen evolution reaction performance of pyrochlore oxide through amorphous/crystalline heterostructure engineering

Efficient and durable electrocatalysts for the oxygen evolution reaction (OER) are vital for advancing renewable energy technologies, particularly in water-splitting systems. Herein, we report a novel surface engineering strategy to enhance the OER performance of Bi 2 Ru 2 O 7 (BRO) pyrochlore oxide by constructing amorphous/crystalline heterostructures. Using four surface treatment agents—nitric acid, hydrogen peroxide, vitamin C, and sodium borohydride—we successfully induced an amorphous RuOx layer on crystalline BRO, significantly increasing specific surface area, oxygen vacancies, and active sites. Among these, vitamin C-treated BRO (BRO-VC) exhibited exceptional OER activity, achieving a low overpotential of 297 mV at 10 mA cm −2 in 1 M KOH, outperforming untreated BRO (349 mV), other treated variants, and commercial RuO 2 (410 mV). Density functional theory (DFT) calculations reveal that the RuO x /BRO heterostructure shifts the d-band center, optimizing adsorption energies of OER intermediates and reducing overpotential. This work demonstrates that tailoring amorphous/crystalline interfaces via surface treatment offers a powerful approach to designing high-performance OER catalysts, providing critical insights into structural engineering for electrocatalytic applications.