The electrochemical oxygen evolution reaction (OER) is an essential anodic reaction that converts sustainable energy into chemical fuels, as it can provide protons and electrons. One of the most challenging research directions for the practical application of the OER is the elevation of the activity of noble-metal-free electrocatalysts. Here, we report that the nickel foam can be used as an electron-deficient substrate to tune the surface oxidation state of catalytic electrodes and thus boost the OER activity of CuP 2 nanosheets via a charge-storage mechanism. The as-obtained self-standing CuP 2 /Ni electrodes delivered a current density of 220 mA cm −2 at 370 mV overpotential, which is approximately 5.5 times higher than the benchmarked IrO 2 on nickel foam. This work sheds some new light on the design of low-cost electrocatalysts or electrodes with high activity for the electrochemical OER.