Laser fabricated binder-free Ni/NiO nanostructured electrodes for enhanced hydrogen evolution

Abstract

The growing demand for green hydrogen via electrochemical water splitting necessitates highly efficient electrocatalysts for the hydrogen evolution reaction (HER). Traditional electrode fabrication methods using organic binders often hinder electron transfer and limit surface area, reducing catalytic performance. Binder-less approaches, such as Ultra-Short Laser Pulses for In-Situ Nanostructure Generation (ULPING), provide an alternative by enhancing electron transfer kinetics and catalytic activity. This study explores the influence of laser fabrication parameters (i.e. laser power and scanning speed) on the growth of nano-Ni/NiO, having broccoli-type morphology, for hydrogen evolution in alkaline media (1 M KOH). SEM and EDX analyses revealed correlations between surface roughness, oxidation, and laser processing conditions, while XPS deconvolution of Ni-2p_3/2 and O-1s spectra provided insights into oxidation states and surface chemistry. Higher laser power increased oxidation and nanostructure formation, leading to enhanced surface area and improved catalytic performance, while lower scanning speeds allowed more ablation time, further improving HER efficiency. Among the four samples studied, sample S3, with highest power and lowest scanning speed, exhibited the best performance with an overpotential of 154 mV at 10 mA/cm², a Tafel slope of 93.8 mV/dec, along with a large ECSA, and stability for 12 hours. Additionally, S3 demonstrated lower charge transfer resistance (R_ct) and higher catalytic turnover frequency (TOF) compared to other samples. These findings establish ULPING as a scalable, reproducible method for fabricating high-performance Ni/NiO electrodes, emphasizing the importance of optimizing fabrication parameters to enhance catalytic activity, in line with the UN’s Sustainable Development Goals (SDGs) for clean energy technologies.