Tuning the Surface Electronic Structure of Amorphous NiWO₄ by Doping Fe as an Electrocatalyst for OER

Abstract

Water electrolysis is considered as one of the alternative potential approaches for producing renewable energy. Due to the sluggish kinetic nature of oxygen evolution reaction (OER), it encounters a significant overpotential to achieve water electrolysis. Hence, the advancement of cost-effective transition metal-based catalysts toward water splitting has gained global attention in recent years. In this work, the doping of Fe over amorphous NiWO4 increased the OER activity effectively and achieved stable oxygen evolution in the alkaline medium, which show better electrocatalytic activity as compared to crystalline tungstate. As NiWO4 has poor activity toward OER in the alkaline medium, the doping of Fe3+ will tune the electronic structure of Ni in NiWO4 and boost the OER activity. The as-synthesized Fe-doped amorphous NiWO4 exhibits a low overpotential of 230 mV to achieve a current density of 10 mA cm–2 and a lower Tafel slope value of 48 mV dec–1 toward OER in 1.0 M KOH solution. The catalyst also exhibits long-term static stability of 30 h during chronoamperometric study. The doping of Fe improves the electronic conductivity of Ni-3d states in NiWO4 which play a dominant role for better catalytic activity via synergistic interaction between Fe and active Ni sites. In future, these results offer an alternative route for precious metal-free catalysts in alkaline medium and can be explicitly used in various tungstate-based materials to increase the synergism between the doped atom and metal ions in tungstate-based materials for further improvement in the electrocatalytic performance.

Research progress of amorphous catalysts in the field of electrocatalysis

“…The obtained amorphous P-doped MoS 2 catalyst delivers better catalytic activity and stability than that of the crystalline MoS 2 in acidic electrolytes. The Fe element was doped in amorphous Ni-P-B-O (NPBO) nanocages to prepare Fe-NPBO (FNPBO) catalysts and their amorphous feature was revealed via XRD patterns [Figure 13A] [119] . The FNPBO, as an OER catalyst, exhibits a smaller overpotential and a smaller Tafel slope than that of NPBO [Figure 13B].…”

“…The factors of the electronic structure and surface acid-base properties that affect the catalytic reactions of amorphous catalysts can be controlled by surface modification. For example, the microstructure of amorphous FNPBO can be adjusted by various Fe/Ni ratios [Figure 14A-F] [119] . The microstructure changes from nanocages to NSs as the Fe/Ni ratio in FNPBO increases, thus altering its OER performance.…”

Binary Ni–Cu nanocomposite-modified MXene-adorned 3D-nickel foam for effective overall water splitting and supercapacitor applications

“…Transition metals such as Mn, Mo, Ni, Cu, Fe and cobalt were observed to be a promising inexpensive alternative, exhibiting good activity towards the both HER and OER. 35–37 Among them, nickel due to its abundant reserves on Earth and good intrinsic catalytic activity has been reported to be suitable for electrochemical water splitting. Other factors including its incredible resistance in basic medium, good binding energy for hydrogen and (111) lattice plane promote the water splitting reaction.…”

Medium-Entropy Co–Fe–Cr–Mo Spinel Nanoflowers as Electrocatalysts for Oxygen Evolution

“…With the overuse of fossil fuels, the current society is at the crossroads of energy crisis and environmental pollution. − Therefore, it is urgent to find a clean energy resource that can replace fossil fuels. Hydrogen is a clean energy source, which can be environmentally generated by water electrolysis.…”