yMoO42- modified amorphous Co(PO3)2 cubes as an efficient bifunctional electrocatalyst for alkaline overall water splitting

The exploration of efficient bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline conditions is an important   way to promote the development of electrolytic water technology . Herein, the reduced graphene oxide-supported MoO 4 2- modified amorphous cobalt metaphosphate cubes (a-Co(PO 3 ) 2 /MoO 4 /rGO) as bifunctional OER/HER catalyst is prepared by anion exchange and phosphating, using the Prussian blue analogue (PBA) as a precursor. The resulting composite exhibits the low overpotentials (η) that of 290 and 50 mV for OER and HER in 1.0 M KOH solution at 10 mA cm −2 , respectively. The electrochemical test and density functional theory (DFT) results reveal that the MoO 4 2- -modified optimizes the adsorption/desorption energy of H* of Co(PO 3 ) 2 , thus enhance the HER activity. Benefiting from efficient HER and OER performances, an efficient and stable alkaline water electrolysis operation using a-Co(PO 3 ) 2 /MoO 4 /rGO used as bifunctional catalyst can be carried out, which can deliver a current density (j) of 20 mA cm −2 at 1.65 V cell voltage and work continuously for 24 h.