# Highly Corrugated Ni Films Electrodeposited onto Boron Doped Diamond Electrodes for Alkaline Water Electrolysis

## TL;DR

Researchers developed a new nickel-based catalyst on diamond electrodes for efficient hydrogen production in alkaline water.

## Contribution

A novel method for fabricating highly corrugated Ni films on BDD electrodes for improved HER performance in alkaline media.

## Key findings

- A dealloyed Ni catalyst achieved a HER overpotential of 152 mV at 10 mA cm–2 in pH 13 KOH.
- HER kinetics are limited by surface diffusion of intermediates and show second-order dependence on Ni active sites.
- Two Tafel slopes indicate a change in HER mechanism and intrinsic activity at the dealloyed Ni catalyst.

## Abstract

Ni-based electrocatalysts are among the most active materials
for
the hydrogen evolution reaction (HER) in alkaline media. In this work,
we demonstrate the ability to use films of boron-doped diamond (BDD),
a stable and corrosion-resistant electrode material, as a support
for highly textured Ni films. Our approach is based on the electrodeposition
of NiCu alloy thin-films, followed by electrochemical dealloying.
The structure and composition of the electrocatalysts were characterized
using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron
spectroscopy. In pH 13 KOH, a dealloyed Ni catalyst corresponding
to an initial NiCu composition of 68% Ni, gave a HER overpotential
at 10 mA cm–2 of 152 mV. With further analysis,
we show that the rate of HER is 2nd order with respect
to the number of Ni active sites, and that the kinetics are limited
by the surface diffusion of adsorbed intermediates. Two Tafel slopes
are additionally observed, suggesting a change in HER mechanism and
intrinsic activity at dealloyed Ni catalysts.