Microfabrication
of the Ammonia Plasma-Activated Nickel
Nitride–Nickel Thin Film for Overall Water Splitting in the
Microfluidic Membraneless Electrolyzer
posted on 2021-09-02, 18:08authored byBiswajit
S. De, Pawan Kumar, Neeraj Khare, Jing-Li Luo, Anastasia Elias, Suddhasatwa Basu
Hydrogen production in the microfluidic
alkaline membraneless electrolyzer
(μAME) marks a new paradigm in sustainable energy technology.
One challenge in this field is implementing a bifunctional catalyst
to catalyze hydrogen evolution reaction and oxygen evolution reaction
using methods compatible with microfabrication techniques. Herein,
the scalable synthesis, micropatterning, and performance of a nickel
nitride (Ni3N/Ni) bifunctional catalyst are demonstrated.
Microfabrication is used to pattern Ni microelectrodes, and nitridation
and N–H grafting of the electrodeswhich also act as
the catalystsare achieved by ammonia plasma. These electrodes
are incorporated into the μAME device, and the electrolyte flow
rate is optimized to maximize gas product separation. The μAME
is operated in a two-electrode configuration exhibiting a current
density of 263.73 mA cm–2 at 2.5 V and a stable
6 h operation for overall water splitting. The μAME performance
efficiency is 99.86%, with a current density of 150 mA cm–2. Gas chromatography of the electrolysis products revealed no gas
cross-over across the electrodes. Volumetric collection efficiencies
of 97.72% for H2 and 96.14% for O2 are obtained.
The performance of the μAME is comparable to a membrane-based
electrolyzer operating under stringent conditions of high temperature
(60–80 °C) and extreme electrolyte pH (30–40 wt
% KOH).