Chemically Etched Prussian Blue Analog–WS₂ Composite as a Precatalyst for Enhanced Electrocatalytic Water Oxidation in Alkaline Media

Abstract

The electrochemical water-splitting reaction is a promising source of ecofriendly hydrogen fuel. However, the oxygen evolution reaction (OER) at the anode impedes the overall process due to its four-electron oxidation steps. To address this issue, we developed a highly efficient and cost-effective electrocatalyst by transforming Co−Fe Prussian blue analog nanocubes into hollow nanocages using dimethylformamide as a mild etchant and then anchoring tungsten disulfide (WS 2 ) nanoflowers onto the cages to boost OER efficiency. The resulting hybrid catalyst-derived oxide demonstrated a low overpotential of 290 mV at a current density of 10 mA cm −2 with a Tafel slope of 75 mV dec −1 in 1.0 M KOH and a high faradaic efficiency of 89.4%. These results were achieved through the abundant electrocatalytically active sites, enhanced surface permeability, and high electronic conductivity provided by WS 2 nanoflowers and the porous threedimensional (3D) architecture of the nanocages. Our research work uniquely combines surface etching of Co−Fe PBA with WS 2 growth to create a promising OER electrocatalyst. This study provides a potential solution to the challenge of the OER in electrochemical water-splitting, contributing to UN SDG 7: Affordable and clean energy.

Synergistically coupling CoS/FeS2 heterojunction nanosheets on a MXene via a dual molten salt etching strategy for efficient oxygen evolution reaction

“…This is because metal suldes are partially oxidized to the corresponding metal oxides/hydroxides under the oxidation potential of the OER, which serve as the active species for the OER. 56 Overall, the delicate nanostructure of MXene@CoS/FeS 2 enables it to exhibit better OER performance than its MXene@Co 0.7 Fe 0.3 , CoS/FeS 2 , MXene@CoS, and MXene@FeS 2 counterparts. This is attributed to the clever regulation achieved through the dual strategy of double-salt etching and in situ sulfurization.…”

“…S28, † indicating that MXene@CoS/FeS 2 still exhibits the best catalytic activity. 56 The electrochemical stability of MXene@CoS/FeS 2 is evaluated through consecutive CV scans and chronoamperometry (i-t) tests. 57 The results demonstrate that the overpotential of MXene@CoS/FeS 2 only increases by 5 mV even aer undergoing 2000 CV cycles (Fig.…”

“…This is because metal sulfides are partially oxidized to the corresponding metal oxides/hydroxides under the oxidation potential of the OER, which serve as the active species for the OER. 56…”

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

“…Now, a question arises: why is Fe–Co simultaneously important at the B-site to regulate/tune the promotional electrocatalytic activity in double perovskite oxides? Although increasing evidence supports the idea that monometallic Fe-based catalysts are not that effective for OER, Co–Fe-based catalysts had showed much better OER performances in alkaline medium. − Furthermore, the specific role of Fe along with Co in the B-site is not only to maximize the oxide surface for formation of a self-assembled oxy-hydroxide layer but also to enhance the overall stability and provide a conducting matrix to the structure under OER condition, as highlighted by Kim et al recently . Above all, Fe along with Co centers enhance the OER performance, facilitating the generation of higher valence Co-species (viz., Co 3+ and/or Co 4+ ), which is regarded as the active species for OER in alkaline medium. − …”