Electrodeposited Trimetallic NiFeW Hydroxide Electrocatalysts for Efficient Water Oxidation

Abstract

Tungsten‐doped Ni−Fe hydroxides fabricated on a three‐dimensional nickel foam through cathodic electrodeposition are proposed as effective oxygen evolution reaction (OER) catalysts for alkaline water oxidation. Incorporating an adequate amount of W into Ni−Fe hydroxides modulates the electronic structure by changing the local environment of Ni and Fe and create oxygen vacancies, resulting in abundant active sites for the OER. The optimized electrocatalyst, with a substantial number of catalytic sites, is found to outperform the well‐established 20 wt% Ir/C electrocatalyst. The catalyst only requires small overpotentials of 224 mV and 251 mV to generate current densities of 10 mA cm−2 and 50 mA cm−2, respectively, at an extremely low Tafel slope. Surface study after long‐term chronopotentiometry (ca. 30 h) reveals that the tungsten dopant undergoes reduction to stabilize the Ni and Fe active sites for predominant water oxidation. This research provides new insight to apply optimum amounts of tungsten doping to enable more significant electronic coupling within Ni−Fe for the chemisorption of hydroxy and oxygen intermediates and greatly improved OER activity.

Oxygen Vacancy‐Enhanced Ternary Nickel‐Tungsten‐Cerium Metal Alloy‐Oxides for Efficient Alkaline Electrochemical Full Cell Water Splitting Using Anion Exchange Membrane

“…The survey spectra (Figure S3) revealed the Ni 2p, Ce 3d, W 4 f and O 1s components and their corresponding deconvolution are presented in Figure 3. In Figure 3a, the deconvoluted Ni 2p 3/2 of NiCeWO x ‐1 and NiCeWO x ‐2 consist of various peaks located at 852.9 eV, 855.6 eV, 857.1 eV and 861.2 eV corresponding to Ni 0 (alloy), Ni 2+ state, Ni 3+ state and satellite peaks [21,51] . The above result suggest that the Ni is chemically oxidized from the substrate and involved in the alloy‐oxide structure formation during hydrothermal process.…”

“…In Figure 3a, the deconvoluted Ni 2p 3/2 of NiCeWO x -1 and NiCeWO x -2 consist of various peaks located at 852.9 eV, 855.6 eV, 857.1 eV and 861.2 eV corresponding to Ni 0 (alloy), Ni 2 + state, Ni 3 + state and satellite peaks. [21,51] The above result suggest that the Ni is chemically oxidized from the substrate and involved in the alloy-oxide structure formation during hydrothermal process. In Figure 3b, the Ce 3d show Ce 3d 3/2 and Ce3d 5/2 spectra with spin-orbital splitting of 18.6 eV, and further deconvolute into various multiple peaks including v 0 , v', u 0 and u' corresponding to the Ce 3 + species, and v, v", u, u" corresponding to the Ce 4 + species.…”

“…[15][16][17][18] On the other hand, noble metals are expensive and scarce of earth. [19][20][21] Therefore, it is attractive to design efficient catalysts for full water splitting related to anion exchange membrane with low-cost and earth-abundant non-noble catalysts and their compounds in recent years. [14,22,23] The most attractive non-noble metal catalysts with high electrical conductivity, broadening metal d-band for efficient OER are Fe, Co, Ni, Mn and their oxides, while W, Mo, Ce and their oxides are regarded as the most considerable HER catalysts.…”

Modulating the Intrinsic Electrocatalytic Activity of Copper Sulfide by Silver Doping for Electrocatalytic Overall Water Splitting

“…Further, the Nyquist plots measured at different OER potentials were given in Figure 6a, which reveals that the charge transfer resistance (R ct ) is decreased with the increasing evolution potential. It demonstrates that the charge transfer was much rapid at higher evolution potential as reflected in the lower charge transfer resistance and the high current density [23,27] . The OER electrocatalytic activity was further validated by the intrinsic catalytic activities evaluation done by turn over frequency (TOF).…”

“…It demonstrates that the charge transfer was much rapid at higher evolution potential as reflected in the lower charge transfer resistance and the high current density. [23,27] The OER electrocatalytic activity was further validated by the intrinsic catalytic activities evaluation done by turn over frequency (TOF). The oxygen turns over rate concerning the active center per unit time can be derived by measuring the number of active sites and normalizing the obtained current density by it.…”