Multi-touch cobalt phosphide-tungsten phosphide heterojunctions anchored on reduced graphene oxide boosting wide pH hydrogen evolution

Multi-interface engineering is deemed as an effective strategy to boost catalytic activity via electronic structure modulation. However, it is still a big challenge due to the phase-separation tendency. Herein, we designed CoP-WP heterojunctions with multi-touch interfaces using Co8W18, a definite structure polyoxometalate-based polynuclear cobalt molecular cluster, as a precursor. The CoP-WP heterojunctions anchored on reduced graphene oxide (CoP-WP/rGO) were obtained by growing Co8W18 on GO followed by phosphorization. The intrinsic {Co-O-W} coordination modes in Co8W18 are conducive to the formation of the multiple interfaces between CoP and WP. The abundant intimate interfaces in CoP-WP heterojunctions promote the electron transfer from WP to CoP, thus regulating the interfacial electronic structure and optimizing the hydrogen adsorption free energy (ΔGH*), as verified by X-ray photoelectron spectroscopy analysis and theoretical calculations. Furthermore, the integration of rGO provides CoP-WP/rGO with a large surface area and high conductivity, aiding mass transport and charge transfer. CoP-WP/rGO exhibits remarkable hydrogen evolution reaction (HER) activity with low overpotentials of 96, 130, and 138 mV at 10 mA cm−2 in alkaline, acidic and neutral media, respectively, and has long-term durability. Our discovery provides an opportunity to design heterojunction materials with multi-coupled interfaces at low-cost and efficient HER catalysts.