Directed Surface Reconstruction of Fe Modified Co 2 VO 4 Spinel Oxides for Water Oxidation Catalysts Experiencing Self-Terminating Surface Deterioration.

Affordable highly-efficient catalysts for electrochemical oxygen evolution reaction (OER) play pivotal roles in green hydrogen production via water electrolysis. Regarding the non-noble metal-based electrocatalysts, considerable efforts have been made to decipher the cation leaching and surface reconstruction, yet little attention is focused on correlating them with catalytical activity and stability. Herein, in situ reconstruction of Fe-modified Co 2 VO 4 precursor catalyst to form a highly active (Fe, V)-doped CoOOH phase for OER is reported, during which partial leaching of V accelerates the surface reconstruction and the V reserved in the reconstructed CoOOH layer in the form of alkali-resistant V 2 O 3 serves for dynamic charge compensation and prevention of excessive loss of lattice oxygen and Co dissolution. Fe substitution facilitates Co pre-oxidation and endows the catalysts with structural flexibility by elevating O 2p band level, hence encouraging participation of lattice oxygen in OER. The optimized Co 2 Fe 0.25 V 0.75 O 4 electrode can afford current densities of 10 and 500 mA cm -2 at low overpotentials of 205 and 320 mV, respectively, with satisfactory stability over 600 h. By coupling with Pt/C cathode, the assembled alkaline electrolyzer can deliver 500 mA cm -2 at a low cell voltage of 1.798 V, better than that of commercial RuO 2 (+) || Pt/C (-). This article is protected by copyright. All rights reserved.