Abstract:
Employing clean energy sources to produce hydrogen from the process of
electrocatalytic water splitting has become one of the long-term solutions to the
problems of depleting energy sources. To develop stable, efficient and non-noble
electrocatalyst for water splitting is very crucial. Because of their low cost, pH
stability and enhanced catalytic activity cobalt and nickel sulfide have become
popular. But due to the problems of low surface area and higher over-potentials, the
supplication of these sulfides is limited. To solve this problem different coupling
techniques of these sulfides with highly active and porous materials have been
employed.
Advancing highly stable and active bifunctional transition metal sulfide-based
electrocatalyst for water splitting is essential for fuel cell technology and the
production of hydrogen. Herein, a three-dimensional hierarchical electrocatalyst in
the form of flower pattern, aligning graphitic carbon nitride sheets with cubic
crystalline Ni-Co sulfide on a nickel foam support, is introduced as a bifunctional
electrocatalyst with an outstanding performance. CoNi2S4GCN heterostructure
prepared by using a hydrothermal method to extend g-C3N4 porous layers, developed
in higher catalytic activity for oxygen evolution and hydrogen evolution reactions
with overpotentials of 310 mV and 160 mV to afford a current density of 30 mA/cm2
and 10 mA/cm2
. It is revealed that the astonishing features of this catalyst lie in the
high porosity and surface area of conductive GCN support, the interfacial bonds
between Carbon, nitrogen and cobalt, nickel sulfide and the three-dimensional
configuration. The electrolyzer displays electrolysis at 1.58 V to reach a current
density of 10 mA/cm2 with long term durability of 24 hours. This approach of
preparing CoNi2S4GCN leads to enhanced kinetics for OER/HER, more exposed
surface area, faster electron transport, enhanced diffusion of electrolyte and opened a
new path of enhancing the catalytic activity of water splitting reactions.
