Pulsed laser ablation production of Ni/NiO nano electrocatalysts for oxygen evolution reaction

Efficient and sustainable materials are requested to overcome the actual major issues related to green energy production. Ni/NiO nanoparticles (NPs, 2–4 nm in size) produced by Pulsed Laser Ablation in Liquid (PLAL) are reported as highly efficient and stable electrocatalysts for oxygen evolution reaction (OER) in water splitting applications. Ni/NiO NPs dispersions are obtained by ablating a Ni target immersed in deionized water with an Nd:YAG nanosecond pulsed laser. NPs size and density were driven by laser energy fluence (ranging from 8 to 10 J cm−2) and shown to have an impact on OER performance. Ni/NiO NPs were characterized by scanning and transmission electron microscopy, x-ray diffraction, photoemission spectroscopy, and Rutherford back-scattering spectrometry. By drop-casting onto graphene paper, anode electrodes were fabricated for electrochemical water splitting in alkaline electrolytes. The extrinsic and intrinsic catalytic performances for OER have been quantified, achieving an overpotential of 308 mV (at a current density of 10 mA cm−2) and unprecedented mass activity of more than 16 A mg−1, using NPs synthesized with the highest and lowest laser energy fluence, respectively. The impact of NPs’ size and density on OER performances has been clarified, opening the way for PLAL synthesis as a promising technique for highly efficient nano-electrocatalysts production.