Because of its advantages such as abundant resources, low cost, simple synthesis, and high electrochemical stability, cobalt phosphide (CoP) is considered as a promising candidate for electrocatalytic hydrogen evolution reaction. Through element doping, the morphology and electronic structure of the catalyst can be tuned, resulting in both the increase of the active site number and the improvement of the intrinsic activity of each site. Herein, we designed and fabricated Mn-doped CoP nanowires with a length of 3 μm, a diameter of 50 nm, and the pores between the grains of 10 nm. As a highly efficient electrocatalyst for alkaline hydrogen evolution, the Mn10-doped CoP/NF (doping amount is about 10 atom %) electrode presented overpotentials of 60 mV @ 10 mA cm–2 and 112 mV @ 100 mA cm–2, improved by 35 and 23%, respectively, compared with CoP/NF. Characterizations indicate that Mn doping increases the electrochemical active area, reduces the impedance, and tunes the electronic structure of the material. Density functional theory calculations also revealed that an appropriate amount of Mn dopant at a suitable location can both react as an active site itself and boost the activity of the surrounding Co sites, delivering favorable H* adsorption and rapid reaction kinetics. This result may not only promote the development of hydrogen evolution reaction catalysts but also encourage explorations of the relationship between the property and fine doping structure.

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Despite the expectation on transition-metal phosphides as precious-metal-free electrocatalysts, the reported performance of these materials still necessitates further improvement. Ingenious regulations of both geometric and electronic structure have been proposed as an effective approach to boost their electrocatalytic properties. In this regard, the selfsupported V doped CoP nanowires on nickel foam are prepared to accommodate both optimized electronic structure and desired nanostructure, which enable large surface area, abundant active sites exposure, low charge transfer resistance, as well as favorable H* adsorption. As for the alkaline hydrogen evolution, it only requires a lower potential of 79 mV and 125 mV to drive 10 mA • cm À 2 and 100 mA • cm À 2 current with a Tafel slope of 47.41 mV • dec À 1 , which prevails over commercial Pt/C catalysts. The catalyst also exhibits excellent durability to retain activity unchanged for more than 16 h. Such a simple and convenient strategy by electronic tuning and structure design provides a new avenue toward the exploration of efficient electrocatalysts.