Amorphous Cobalt Iron Borate Grown on Carbon Paper as a Precatalyst for Water Oxidation

Abstract

The key to improving water oxidation is to develop efficient and earth‐abundant catalysts for the oxygen evolution reaction (OER). Herein, a new amorphous cobalt iron borate supported on 3D carbon paper integrated electrode is reported as a precatalyst for the OER, which was synthesized by using a one‐pot hydrothermal method. An optimum OER activity was obtained at 25 % Fe doping by screening the compositions of the Co and Fe. The best synthesized catalyst needs an overpotential of 227 mV to deliver a current density of 10 mA cm−2 and also exhibits a long‐term durability of 24 h. Impressively, we find that CoFe oxyhydroxide was formed in situ in the OER process, which serves as the real catalytic active species for OER. Moreover, the direct conversion from CoFe borate to CoFe oxyhydroxide is reported for the first time in metal borate OER catalysts. The discovery in this work, that is, that metal borate as a precursor can efficiently catalyze the OER in alkaline media, significantly widens the family of OER catalysts.

Ultra-small Ru nanoparticles embedded on Fe–Ni(OH)2 nanosheets for efficient water splitting at a large current density with long-term stability of 680 hours

“…S4†) indicates that the valence of Fe is 3+. 38–40 X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra were used to probe the chemical valence and surrounding coordination environment of the prepared catalysts. As shown in Fig.…”

Fe-Based Electrocatalysts for Oxygen Evolution Reaction: Progress and Perspectives

“…The boronized NiFe alloy exhibited higher intrinsic catalytic activity, compared to the state-of-the-art materials in 1 M KOH, while presenting excellent catalytic stability for over 3000 h (see Figures 12b and 12c). Cao et al 180 also found that amorphous CoFe bimetallic borates experienced a direct transformation from CoFe borate to CoFeOOH during the OER measurement and the CoFeOOH served as effective catalytic centers within the OER process. Furthermore, the generation of mixed-metal oxide/(oxy)hydroxide through in situ electrochemically transformation has also been reported for transition-metal sulfides and selenides.…”

“…The boronized NiFe alloy exhibited higher intrinsic catalytic activity, compared to the state-of-the-art materials in 1 M KOH, while presenting excellent catalytic stability for over 3000 h (see Figures b and c). Cao et al also found that amorphous CoFe bimetallic borates experienced a direct transformation from CoFe borate to CoFeOOH during the OER measurement and the CoFeOOH served as effective catalytic centers within the OER process. Furthermore, the generation of mixed-metal oxide/(oxy)­hydroxide through in situ electrochemically transformation has also been reported for transition-metal sulfides and selenides. ,,− It is widely accepted that metal oxides are thermodynamically more stable than metal sulfides under highly oxidizing conditions and metal phosphides and metal nitrides are less stable than metal sulfides. , Therefore, the mixed-metal compounds have a high possibility of being transformed to oxide/(oxy)­hydroxide during OER measurement (Figure d).…”

Molten-Salt-Protected Pyrolytic Approach for Fabricating Borate-Modified Cobalt–Iron Spinel Oxide with Robust Oxygen-Evolving Performance

“…Hydrogen production via water electrolysis is regarded as a promising technique for developing clean energy to replace fossil fuels. − Considering the sluggish reaction kinetics of the oxygen evolution reaction (OER), designing earth-abundant OER catalysts with high catalytic activity and satisfied operational stability is of great importance for further improving the overall efficiency of water splitting. − To date, great efforts have been devoted to the exploration of transition metal-based OER catalysts in various structures, including spinel structures, − layered structures, − perovskite structures, − amorphous structures, ,− and so forth. Aiming on improving the OER activity, enriching the active sites (or facilitating the in situ formation of active species via preoxidation reactions) and enhancing the intrinsic activity of the single site are two basic principles .…”