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In meeting the energy demand of green resources, the fabrication of effective yet cheap electrocatalytic active catalysts for the rate‐limiting half reaction, oxygen evolution reaction (OER), of electrochemical water splitting is highly desired. In this study, it is presented that a deliberately deposited amorphous FeOOH layer can drastically promote the electrocatalytic OER activity of CoSe2. Unlike the pristine CoSe2 which is consumed gradually, the amorphous FeOOH layer facilitates the capture and fixation of dissolved Co2+ ions, which is confirmed by the stable element contents during OER process. As a result, a low overpotential of 253 mV (@ j = 40 mA cm−2) is displayed by CoSe2@FeOOH nanorod arrays (NAs) on carbon cloth (CC) with a small Tafel slope of 69 mV dec−1, which are comparable or even lower than the state‐of‐the‐art OER electrocatalysts. In addition, the long‐time durability test indicates the remarkable stability of this material over 20 h. These outcomes provide new perception in design and large scale fabrication of cheap yet effective heterostructured OER catalysts.

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Herein, CoNi bimetallic metal‐organic framework nanosheets (CoNi−MOFNs) in‐situ grown on Ti3C2Tx MXene (CoNi−MOFNs@MX) were explored as a typical nanocomposite to study the impact of MXene on the electrocatalytic activity of MOF for oxygen evolution reaction (OER). In contrast to previous reports, we observed a passive effect of Ti3C2Tx MXene on the OER performance of CoNi−MOFNs although the electronic conductivity of the nanocomposites was improved. The combined analysis of electrochemical results and atomic valence state characterization demonstrates that the decreased OER activity is likely ascribed to the unfavorable electron donation from Ti3C2Tx MXene, which suppresses the formation of active species for OER from the oxidation of Co2+ and Ni2+ to higher valence states in the nanocomposite. Consequently, more attention needs to be paid to the rational design of nanocomposites with MXenes for electrocatalytic applications.

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