Localizing electrons on atomic platinum by metal phosphides for accelerating electrocatalytic hydrogen evolution

The development of the electrical metal-support interaction for boosting alkaline hydrogen evolution reaction (HER) is essential for the high catalytic performance of Pt-based single atom catalysts (SACs). Herein, we design the Pt single atoms immobilized Ni2P nanosheet arrays on the nickel foam (Pt-SA-Ni2P@NF) to construct a 3D hierarchical nanostructure as an alkaline HER catalyst. It is found that the 3D continuous NF and the conductive Ni2P array support provide an efficient electron transport path for Pt single atoms, which can significantly reduce the charge transfer impedance and increase the electrochemical active sites to accelerate HER process in the alkaline electrolyte. Density functional theory calculations and structural analytical data confirm that Pt-SA-Ni2P@NF displays the suitable interaction between Pt single atoms and Ni2P support with the formation of Pt-P bonds at the interface, contributing to the high electric field intensity to provide more localized free electrons for accelerating H2O dissociation process to enhance the favorable H* adsorption and H-2 release. The energy required to remove adsorbed H from the reaction site for our Pt-SA-Ni2P@NF is found to be the lowest for Pt-SA-Ni2P@NF (Delta E = 0.05 eV). Electrocatalytic experiments exhibit that Pt-SA-Ni2P@NF displays the outstanding HER activity with a low overpotential of 26 mV at a current density of 10 mA cm(-2). The mass activity (19.2 mg(Pt)(-1)) of Pt-SA-Ni2P@NF is 43.6 times higher than that of the commercial benchmark catalyst (0.4 A mg(Pt)(-1), 20 % Pt/C).