Synergy of Cobalt Iron Tetrathiomolybdate Coated on Cobalt Iron Carbonate Hydroxide Hydrate Nanowire Arrays for Overall Water Splitting

Abstract

Electrochemical water splitting is regarded as an ideal strategy for producing hydrogen energy. However, the ability to design efficient and durable noble-metal-free catalysts for decreasing the overpotential in the electrolysis process is in high demand.Here, it is demonstrated that cobalt iron carbonate hydroxide hydrate nanowire arrays on Ti mesh (CFOC/TM) obtained through a surface anion interchange method can lead to amorphous cobalt iron tetrathiomolybdate coated on crystalline cobalt iron carbonate hydroxide hydrate nanowire arrays on Ti mesh (CFMS@CFOC/TM), which can act as an efficient and durable water splitting electrocatalyst in alkaline media. CFMS@CFOC/TM shows good performance for the oxygen evolution and hydrogen evolution reactions, with the need for low overpotentials of 237 mV and 93 mV at 10 mA cm À 2 in 1.0 M KOH, respectively. As a 3D bifunctional electrode catalyst, it enables alkaline water splitting with excellent performance, achieving 10 mA cm À 2 at a voltage of 1.63 V with a satisfying stability performance.The exploitation and utilization of fossil fuels have leaded to environmental degradation and fossil energy depletion, [1][2][3][4] therefore, it is urgent to search for low-priced, cleaning, and renewable energy resources. Hydrogen energy is expected to substitute fossil energy due to its high calorific value and noncarbonaceous peculiarity. [5][6][7][8] Electrochemical water splitting contained simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is regarded as one of the most significant routes for producing hydrogen, [9][10][11] but it is still limited by some factors. The dominant limitation is the large overpotential in water splitting process, therefore, efficient catalysts must be used to accelerate reaction rate and reduce overpotential. In conventional commercial production, Pt is the highest HER catalyst while RuO 2 is the optimal OER catalyst, nevertheless, the scarcity and costliness of those catalysts hinder their wide uses. [12,13] Accordingly, it is highly desired to develop efficient non-noble bifunctional catalysts for water splitting.Transition metal layered double hydroxides are considered to promising materials for OER to reduce the overpotential and promote electrolysis efficiency, [14][15][16][17][18] however, most of them have poor catalytic performance toward HER. As we all know, transition metal tetrathiomolybdate show remarkably efficient catalytic performance in HER. [19][20][21] For improving both HER and OER in water splitting, the coupling of HER and OER catalysts is significant. [22,23] Currently, many researches focus on combining the advantages of HER-and OER-efficient materials to construct core-shell structures, [24][25][26][27] increasing catalytic activity benefited from the large defect-rich at the hetero interface. Inspired by this, we expect to convert transition metal hydroxides at the surface into transition metal tetrathiomolybdate to achieve efficient performance of both HER and OER.Here, we demonstrate the ...

Cubic Nanostructures of Nickel–Cobalt Carbonate Hydroxide Hydrate as a High-Performance Oxygen Evolution Reaction Electrocatalyst in Alkaline and Near-Neutral Media

“…Similarly, in NiFe LDH systems, the incorporation of iron and its percentage affected the OER activity, as studied by Trotochaud et al, who found that 25% of iron with nickel showed high OER activity . Hence, it will be indeed interesting to try different combinations of carbonate hydroxides with different molar ratios for enhancing the OER activity in different pH conditions. − In addition, several other reports highlighted the use of transition-metal-based carbonate hydroxides as effective catalysts for OER and total water splitting applications. − …”

Mixed Transition Metal Carbonate Hydroxide‐Based Nanostructured Electrocatalysts for Alkaline Oxygen Evolution: Status and Perspectives

“…There are various modulation strategies for improving the OER kinetics and decreasing the overpotential of MTMCHs for alkaline OER. [ 55–57,68,72–99 ] Table 1 summarizes the different approaches undertaken to achieve excellent OER performance with the good long‐term stability of MTMCHs.…”

“…Reproduced with permission. [ 95 ] Copyright 2020, Wiley‐VCH GmbH. d) Schematic illustration of the formation of Cu 3 N@CoNiCHs@CF and e) TEM image of Cu 3 N@CoNiCHs showing the core–shell structure.…”

“…According to previous studies, introducing a heterointerface of crystalline and amorphous components can be a feasible approach to superior electrocatalytic activity. [ 150,151 ] Zhao et al [ 95 ] adopted this strategy and fabricated a 3D heterostructure composed of amorphous cobalt–iron tetrathiomolybdate shell on crystalline Ti mesh‐supported cobalt–iron carbonate hydroxide hydrate nanowire arrays (CFMS@CFOC/Ti mesh), as shown in Figure 10c. The hypothesis was that such an amorphous–crystalline combination would accelerate the charge transfer by increasing exposure of the active sites to the electrolyte and also improve the long‐term structural stability of the electrode material.…”

“…Figure displays a pie chart of the available reports on the electrocatalytic alkaline OER activities of transition metal carbonate hydroxides to date. [ 55–57,59,60,67–99 ] The present review commences with a general discussion of the electrochemical pathways and mechanism of OER in alkaline media. Subsequently, all the activity‐determining parameters in the OER and comprehensive studies on first‐row transition‐metal‐based multimetallic MTMCHs as OER electrocatalysts are discussed.…”