Tailoring the d-band centers of FeP nanobelt arrays by fluorine doping for enhanced hydrogen evolution at high current density

Modulating the intrinsic activity of transition metal iron-based phosphates though tailoring d-band center has been effective strategy especially for large-scale hydrogen production at high current density. Herein, nonmetallic fluorine atoms are well doped into FeP nanobelt arrays by room temperatures immersion method for enhanced performance of hydrogen evolution reaction (HER) in alkaline solution. Significantly, the optimized fluorine-doped iron phosphide nanobelt array (3F-FeP) possess enhanced HER catalytic activity with low overpotentials of 191, 261 and 302 mV to achieve the 100, 500 and 1000 mA cm−2. Furthermore, the long-time stability test indicates that the NiFe-LDH/IF(+)//3F-FeP/IF(−) couple can last for more than 100 h at high current density of 1000 mA cm−2, which gives it a great potential in the practical electrolytic water industry. Density functional theory (DFT) calculations and ultraviolet photoemission spectroscopy (UPS) characterization consistently reveal that the doping of F can effectively regulate the electronic structure, promote electron transport, lower the d-band center position, optimize the hydrogen adsorption energy, reduce the water splitting energy and the H2 formation energy of iron phosphate. This work can provide a facile method for the designing strategy of materials with higher catalytic activity for HER.