Co-Ni-P Nanoneedle Array Heterostructures with Built-In Potential for Selective Methanol Oxidation Coupled with H2 Evolution

Electro-oxidation of methanol (MOR) coupling with thehydrogenevolution reaction (HER) is a meaningful innovation strategy to realizeenergy-saving production of H-2 and value-added chemicalproducts. In this study, a self-supported cobalt nickel bimetallicphosphide nanoneedle array (Co-Ni-P/NF) is designedto realize excellent bifunctional activity for the HER and MOR. Studiesprove that the p-n heterogeneous junctions formed in betweennickel phosphide and cobalt phosphide promote the accumulation ofelectrons on CoP, favoring the absorption of H* and boosting HER activity,whereas the increased MOR activity is due to in situ generated holesin Ni2P. Benefiting from the optimized interface/surfaceelectronic structures, the Co-Ni-P/NF produces 100 mAcm(-2) current density in a two-electrode electrolyzerwith a significantly low cell voltage of 1.45 V. The faradic efficienciesup to 100% for both the HER and MOR are obtained, showing the excellentbifunctional catalytic activity of Co-Ni-P/NF nanoneedlearrays. This work throws light on developing novel bifunctional electrocatalystsfor value-added chemical production and highly efficient hydrogenevolution.