In‐situ Tailoring Cobalt Nickel Molybdenum Oxide Components for Overall Water‐Splitting at High Current Densities

Abstract

Developing non‐precious bifunctional electrocatalysts to drive the over water splitting that can operate well at high current densities (1,000 mA/cm2) is an urgent requirement for viable electrolysis of water. Transition metal oxides (TMO) have been intensely investigated as one of the most efficient oxygen evolution reaction (OER) catalysts. Unfortunately, their sluggish reaction kinetics towards hydrogen evolution reaction (HER) bring about poor overall performance. In this study, we perform a simple method to obtain the bifunctional TMO‐based electrocatalyst by in‐situ tailoring the components of cobalt nickel molybdenum oxide on nickel foam. By optimizing the annealing temperature and reaction atmosphere, we integrate HER‐active (CoMoNi) and OER‐active (CoMoOx) components together as bifunctional electrocatalysts for overall water splitting. Impressively, the as‐synthesized electrocatalyst shows the high electrocatalytic activity for both OER and HER, and exhibit a low cell voltage of 1.59 V at 10 mA cm−2 when applied as both the cathode and anode in alkaline solutions. Impressively, the bifunctional electrocatalysts work well at large current densities, even in the order of 1,000 mA cm−2 (only need the cell voltage of ∼2.03 V), and remain its activity more than 20 h. Such an outstanding performance should be mainly attributed to integrated high electronic conductivity, 3D self‐supported structure, and good compatibility between HER‐active and OER‐active components. This study shows a positive model for the design of more promising and practical catalysts for full water splitting.

Fe‐Doped Ni3S2 Nanowires with Surface‐Restricted Oxidation Toward High‐Current‐Density Overall Water Splitting

“…Up to now, the benchmark catalyst for OER is IrO 2 or RuO 2 , while that for HER is Pt/C due to their high activities. However, the high cost and scarcity as well as unsatisfactory durability severely preclude their large scale application . Thus, it is highly desirable to explore electrocatalysts from earth‐abundant materials with low overpotential and excellent durability for OER and HER.…”

“…However, the high cost and scarcity as well as unsatisfactory durability severely preclude their large scale application. [5] Thus, it is highly desirable to explore electrocatalysts from earth-abundant materials with low overpotential and excellent durability for OER and HER. In the past few years, 3d transition metal (such as Ni, Co, Fe, and Mn) compounds were implemented as electrocatalysts for OER and HER because the catalytic performance can be tailored by their composition and structure.…”

Ternary Ni‐Mo‐P catalysts for enhanced activity and durability in proton exchange membrane water electrolysis

“…Mo 3d spectra were observed at 227.9 to 231.1, 229.7‐232.9, and 232.1‐235.3 eV. Peaks at 227.9 to 231.1 eV were attributed to Mo 0 , while peaks at 229.7 to 232.9 and 232.1 to 235.3 eV corresponded to MoO 2 and MoO 3 , respectively 53 . The binding energy of Ni shifted negatively when Mo was added.…”

Self‐Supporting Electrodes for Gas‐Involved Key Energy Reactions

“…[41][42][43][44][45][46][47] It should be noted that there are high interaction forces between the substrate and the material, leading to a single direction growth orientation and uniform dispersion. In comparison to the traditional powder electrode materials, substrate based selfsupporting system has the following advantages: I, lowers the cost without using high-price binder; II, direct use as working electrode; III, excellent operation durability; [48][49][50][51][52] and IV, strong catalyst-substrate interactions. Additionally, self-supporting structured catalysts often feature high electrical conductivity, large electrochemical surface area, increased number of active sites, and accelerated charge transfer rate.…”