Accelerated bubble departure and reduced overpotential with nanoengineered porous bifunctional Ni5P4 electrocatalyst for PV-driven water splitting

Solar-driven green hydrogen production is a promising sustainable technology though large-scale solar water splitting remains challenging due to expensive electrocatalyst. Herein, we propose a facile and low-cost approach to fabricate nanoengineered hierar-chically porous Ni5P4 electrocatalyst (p-Ni5P4), which provides high surface area and en-ables fast gas diffusion. By coating p-Ni5P4 on Ni foam (NF), p-Ni5P4@NF has pores ranging from 50-500 nm to 200-600 mm and enlarges the electrochemically-active surface area by 5 times. p-Ni5P4@NF offers abundant cavities for gas nucleation and fast growth of H2 bubble, and small bubbles (10-50 mm) depart quickly owing to the reduced contact line. By enhancing gas transfer and reducing bubble overpotential over 29%, p-Ni5P4@NF achieves excellent electrocatalytic performance with a low HER (145 mV), OER (197 mV) and overall water splitting potential (1.54 V) at 10 mA cm-2. Powered by multijunction PV cell, the full electrolytic cell records a high solar-to-hydrogen efficiency of 14.5%.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.