High intrinsic activity of the oxygen evolution reaction in low-cost NiO nanowall electrocatalysts. Issue 6 (24th August 2020)

• Record Type: Journal Article
• Authors: Cosentino, Salvatore; Urso, Mario; Torrisi, Giacomo; Battiato, Sergio; Priolo, Francesco; Terrasi, Antonio; Mirabella, Salvo
• Is Part Of: Materials advances. Volume 1:Issue 6(2020)
• Page Start: 1971
• Page End: 1979
• Publication Date: 2020-08-24
• Subjects: 620.11
• DOI: 10.1039/d0ma00467g
• Languages: English
• ISSNs: 2633-5409

Abstract

Abstract : NiO nanowalls grown by low-cost chemical bath deposition and thermal annealing are a high-efficiency and sustainable electrocatalytst for OER. Abstract : Earth-abundant materials for electrochemical water splitting typically show a lower efficiency than noble and rare metal electrocatalysts. Nanostructuring and appropriate material design can largely improve the performances of low-cost electrocatalysts, opening the route towards profitable mass production. Here, we report on a quantitative investigation of the oxygen evolution reaction (OER) on Ni-based nanowall (NW) electrodes. The NiO and Ni(OH)2 NW films (200 or 400 nm thick) are produced by chemical bath deposition followed by calcination at 350 °C. The morphology and the chemical arrangement of the NW were studied, before and after the OER, by scanning electron microscopy, energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The OER electrocatalytic activity was investigated by electrochemical measurements under alkaline conditions (1 M KOH), demonstrating a stable overpotential of 345 mV at 10 mA cm −2, a Tafel slope of 48 mV dec −1 and an O2 turnover conversion frequency (TOF) of up to 0.18 s −1 . The quantitative measurement of active electrocatalysts, through cross-correlation of the experimental data, shows nearly 100% material utilization in the 200 nm NiO NW. In thicker NiO or Ni(OH)2 NW films this fraction decreases below 60%, probably due to the decrease in the electric potential along the nanostructure, as revealed by numerical simulation. These data and discussion support the use of low-cost Ni-based nanostructures for high-efficiency and sustainable electrocatalysts.