Controllably Alloyed, Low Density, Free-standing Ni-Co and Ni-Graphene Sponges for Electrocatalytic Water Splitting

Abstract

Synthesis of low cost, durable and efficient electrocatalysts that support oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are the bottlenecks in water electrolysis. Here we propose a strategy for the development of controllably alloyed, porous, and low density nickel (Ni) and cobalt (Co) based alloys - whose electrocatalytic properties can be tuned to make them multifunctional. Ni and Co based alloy with the chemical structure of Ni1Co2 is identified as an efficient OER catalyst among other stoichiometric structures in terms of over potential @ 10 mAcm−2 (1.629 V), stability, low tafel slope (87.3 mV/dec), and high Faradaic efficiency (92%), and its OER performance is also found to be on par with the benchmarked IrO2. Tunability in the porous metal synthesis strategy allowed the incorporation of graphene during the Ni sponge formation, and the Ni- incorporated nitrogen doped graphene sponge (Ni-NG) is found to have very high HER activity. A water electrolysis cell fabricated and demonstrated with these freestanding electrodes is found to have high stability (>10 hours) and large current density (10 mAcm−2 @ 1.6 V), opening new avenues in the design and development of cost effective and light weight energy devices.

High‐Performance Electrocatalysts for Hydrogen Evolution Reaction Using Flexible Electrodes Made up of Chemically Modified Polyester Films

“…Hence the bimetallic Ag/Ni/OHP flexible electrode is identified to be a better electrocatalyst for HER when compared to other electrodes. The calculated Tafel slope values and the overpotential values are compared with other reported values corresponding to non‐Pt based catalysts and the comparison is shown in Table . It can be seen that the overpotential and Tafel slope values are comparable to many other reports .…”

“…The calculated Tafel slope values and the overpotential values are compared with other reported values corresponding to non‐Pt based catalysts and the comparison is shown in Table . It can be seen that the overpotential and Tafel slope values are comparable to many other reports . Nevertheless this is a new report on chemically modified OHP films being demonstrated as flexible electrocatalysts for HER in alkaline medium that could find potential applications in portable, flexible and minaturized devices used for alkaline water electrolysis.…”

Transition metal ions regulated oxygen evolution reaction performance of Ni-based hydroxides hierarchical nanoarrays

“…The development of improved Ni-based OER catalysts can be accelerated by an improved understanding of the intrinsic catalytic activity of materials and their dependence on catalyst composition and structure. The OER activity of Ni-based catalysts can be significantly enhanced by doping with other earth-abundant elements such as Co, Fe, Mn, and Zn171819202122. Therefore, a systematic study of the OER activities achieved when different dopants are added to Ni-based hydroxides would provide valuable insight into the synthesis of improved OER catalysts23.…”

Non‐Precious Metal/Metal Oxides and Nitrogen‐Doped Reduced Graphene Oxide based Alkaline Water‐Electrolysis Cell

“…The OER process at the anode side is considered to be the major cause of high overpotential in AAEMWE/AWE‐based water electrolysers . Tremendous efforts have been put forth by various researchers to develop transition‐metals‐ and metal‐oxides‐based catalysts and their composites as anode materials for AAEMWE because of their reversible redox reactions, high reaction rates, environmental friendliness and high catalytic activities . In the past few decades, researchers have been working on the development of noble‐metal‐free electrocatalysts (particularly those based on Ni and Co) for the electrocatalytic water splitting .…”