Interfacial electron transfer in heterojunction nanofibers for highly efficient oxygen evolution reaction

Efficient catalysts for the oxygen evolution reaction (OER) are critical to the progress of electrochemical devices for clean energy conversion and storage. Although heterogeneous electrocatalysts have superior activity, it is a great challenge to elucidate electron transfer at surface catalytic sites and intrinsic mechanisms. Herein, we demonstrate a new type of heterostructure electrocatalyst in which Sr0.9Ce0.05Fe0.95Ru0.05O3 fibers are hybridized with in situ grown RuO2 nanoparticles (SCFR–RuO2). We investigate its unique structure, electron transfer mechanisms related to the highly OER activity by combining experimental and theoretical calculations. Remarkably, SCFR–RuO2 shows an optimized OER overpotential of 295 mV at 10 mA cm−2. The promoted electron transfer and OER kinetics are ascribed to the coupling of electronic effects at the SCFR–RuO2 heterostructure. A strong triangular relationship among overpotential–Tafel slope–work function is proposed to be a potential descriptor of OER activity in SCFR–RuO2. These insights provide guidelines for tuning the OER performance via modified work functions in perovskite electrocatalysts.