Enhancing Oxygen Evolution Electrocatalysis via the Intimate Hydroxide-Oxide Interface.

The development of electrocatalysts with high activity and stability for oxygen evolution reaction (OER) is critically important, the one being regarded as the bottleneck process of overall water splitting. Herein, we fulfill significant OER improvement in both activity and stability by constructing a class of Ni(OH)-CeO supported on carbon paper (Ni Ce @CP) with an intimate hydroxide (Ni(OH))-oxide (CeO) interface. Such interface largely promotes the OER activity with a low overpotential of 220 mV at 10 mA cm and a small Tafel slope of 81.9 mV dec in 1 M KOH. X-ray photoelectron spectroscopy analysis shows that the intimate interface induced by the strong electronic interactions between Ni(OH) and CeO involves the modulation of binding strength between intermediates and catalysts, making a great contribution to the OER enhancement. Importantly, such intimate interface structures can be largely maintained even after a long-time stability test. We have further demonstrated that, when pairing the NiCe@CP after phosphorization (P-NiCe@CP), the NiCe@CP and P-NiCe@CP assembly is highly active and stable for overall water splitting with a low voltage of 1.68 V at 25 mA cm and negligible stability delay over 30 h of continuous operation, which are much better than the commercial Ir/C and Pt/C.