A nanostructured MoO2/MoS2/MoP heterojunction electrocatalyst for the hydrogen evolution reaction

Electrocatalytic production of hydrogen from water is considered to be a promising and sustainable strategy. In this work, the low-cost nanostructured MoO2/MoS2/MoP heterojunction is successfully synthesized by phosphorization of the pre-prepared urchin-like MoO2/MoS2 nanospheres as the stable, highly efficient electrocatalysis for the hydrogen evolution reaction (HER). The MoO2/MoS2/MoP-800 (MoO2/MoS2 nanospheres are phosphated at 800 °C) displays a catalytic ability for the HER with an overpotential of 135 mV to achieve 10 mA cm-2 and a Tafel slope of 67 mV dec-1 in 0.5 M H2SO4, which is superior to MoO2/MoS2 nanospheres (200 °C; 24 h), MoO2/MoS2/MoP-700 (MoO2/MoS2 nanospheres are phosphated at 700 °C) and MoO2/MoS2/MoP-900 (MoO2/MoS2 nanospheres are phosphated at 900 °C). Meanwhile, the catalyst exhibits superior properties for HER with an overpotential of 145 mV to achieve 10 mA cm-2 and a Tafel slope of 71 mV dec-1 in 1 M KOH solution. Detailed characterizations reveal that the improved HER performances are significantly related to P-doping and the spherical nanostructure. This work not only provides a low-cost selective for electrocatalytic production of hydrogen, but also serves as a guide to optimize the composition and structure of nanocomposites.