P and Se Binary Vacancies and Heterostructures Modulated MoP/MoSe2 Electrocatalysts for Improving Hydrogen Evolution and Coupling Electricity Generation.

Abstract

It is not enough to develop an ideal hydrogen evolution reaction (HER) electrocatalysts by single strategy. Here, the HER performances are significantly improved by the combined strategies of P and Se binary vacancies and heterostructure engineering, which is rarely explored and remain unclear. As a result, the overpotentials of MoP/MoSe2 -H heterostructures rich in P and Se binary vacancies are 47 and 110mV at 10mAcm-2 in 1m KOH and 0.5m H2 SO4 electrolytes, respectively. Especially, in 1m KOH, the overpotential of MoP/MoSe2 -H is very close to commercial Pt/C at the beginning and even better than Pt/C when current density is over 70mAcm-2 . The strong interactions between MoSe2 and MoP facilitate electrons transfer from P to Se. Thus, MoP/MoSe2 -H possesses more electrochemically active sites and faster charge transfer capability, which are all in favor of high HER activities. Additionally, Zn-H2 O battery with MoP/MoSe2 -H as cathode is fabricated for simultaneous generation of hydrogen and electricity, which displays the maximum power density of up to 28.1mWcm-2 and stable discharging performance for 125h. Overall, this work validates a vigorous strategy and provides guidance for the development of efficient HER electrocatalysts.