A Minireview on Nickel‐Based Heterogeneous Electrocatalysts for Water Splitting

Abstract

developing non-precious electrocatalysts with high performance is of primary significance in a fascinating and scalable water splitting technology for hydrogen production. A number of nickel (Ni)-based heterogeneous catalysts have been designed and synthesized to lower the overpotentials for large current densities due to low cost and facile synthesis. Herein, recent progress on Ni-based composites functioning on hydro-gen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting is summarized. The synthesis strategies, structure design and performance analysis of Nibased heterostructured catalysts are thoroughly discussed, aiming to promote the development of highly efficient electrocatalysts that may ultimately replace the noble-metal based catalysts and bring water splitting into the practical application.Yuting Li, a Ph.D. student in the Department of Chemical Engineering at Nanjing University of Science and Technology. Her research interests focus on the rational design and synthesis optimization of bifunctional composites and structure control of non-noble-metal heterogeneous nanomaterials for electrocatalyzing water splitting.

High intrinsic activity of the oxygen evolution reaction in low-cost NiO nanowall electrocatalysts

“…[11][12][13] In particular, Ni-oxide nanomaterials are well-assessed Earth abundant materials for efficient OER, especially in combination with other metal dopants. 4,5,11,[14][15][16] NiO-based nanostructures have already shown very proficient catalytic actions in sensing, electrochromical smart windows, supercapacitors and energy applications. [17][18][19][20][21][22][23] Such materials have great potential to work also as an efficient backboneplatform electrocatalyst for both the HER and the OER.…”

“…[24][25][26][27] Ni-based nanostructures are thus extremely appealing as a full water splitting cell can be realized with bi-functional heterogeneous electrocatalytic sites for the HER and the OER. 16 It has been recently shown that Ni-Co-Fe sulphide nanosheets on Ni nanocones act as high performance electrocatalysts for total electrochemical water splitting at a potential of 1.54 V to give a current density of 10 mA cm À2 . 28 Similarly, Fe 2+ -doped layered double (Ni, Fe) hydroxides are used for overall water splitting showing an overpotential of 1.54 V to give a current density of 10 mA cm À2 .…”

“…30,31 Actually, there is currently great efforts within the materials science community to find electrocatalysts with superior performance for water splitting, and the nanotechnology approach greatly supports the progress in this direction. 4,5,16 Nonetheless, while many papers report encouraging enhancements of the catalytic action when Ni(oxide) nanostructures are mixed with other elements, a net discrimination of the doping effect over the nanostructure advantages and a fundamental understanding of both are sometimes missing. In addition, a high loading of material electrocatalysts, as typically occurs for Earth abundant elctrocatalysts, could be as expensive as for noblemetal electrocatalysts due to their lower intrinsic activity.…”

Nickel is a Different Pickle: Trends in Water Oxidation Catalysis for Molecular Nickel Complexes

“…[35,45] As the OÀ O bond formation is not the ratedetermining step, it is difficult to establish from the kinetics if this nickel catalyst follows the mononuclear water nucleophilic attack or the dinuclear radical oxo coupling mechanism. [19,23] The order in 1 was determined by performing water oxidation at different complex concentrations. Figure 6b shows that the data can be linearly fitted if we plot the oxygen evolution rate versus the square root of the catalyst concentration.…”

“…[20][21][22] In proton-exchange membrane (PEM) cells, iridium is often used as catalyst at the anode, while in alkaline electrolyzers the catalyst is typically based on nickel. [3,23,24] Inspired by photosystem II in nature, [25][26][27][28] a significant amount of research has been devoted to develop molecular WOCs. These systems have the advantage of being easier to study, as well as being more active per metal center.…”