Electrocatalytic Water Oxidation Activity-Stability Maps for Perovskite Oxides Containing 3d, 4d and 5d Transition Metals

Improving catalytic activity without loss of catalytic stability is one of the core goals in search of low-iridium-content oxygen evolution electrocatalysts under acidic conditions. Here, we synthesize a family of 66 SrBO₃ perovskite oxides (B=Ti, Ru, Ir) with different Ti : Ru : Ir atomic ratios and construct catalytic activity-stability maps over composition variation. The maps classify the multicomponent perovskites into chemical groups with distinct catalytic activity and stability for acidic oxygen evolution reaction, and highlights a chemical region where high catalytic activity and stability are achieved simultaneously at a relatively low iridium level. By quantifying the extent of hybridization of mixed transition metal 3d-4d-5d and oxygen 2p orbitals for multicomponent perovskites, we demonstrate this complex interplay between 3d-4d-5d metals and oxygen atoms in governing the trends in both activity and stability as well as in determining the catalytic mechanism involving lattice oxygen or not.     

Enhanced Electron Transfer and Ion Transport by Binary and Multidimensional CuCo2S4/Fe2O3 on Carbon Cloth for Water Oxidation

The behavior of electron transfer and ion transport plays a significant role in the electrocatalytic activity. However, the improvement of CuCo₂S₄ electrocatalytic activity has been a difficult problem owing to lack of effective electron transfer and ion transport. Herein, the unique structure connected CuCo₂S₄ nanosheets and carbon cloth (CC) with Fe₂O₃ nanoparticles to form CuCo₂S₄/Fe₂O₃/CC. Compared with CuCo₂S₄/CC, the resistances of electron transfer and ion transport were decreased by 65 and 84 %, respectively. The electrochemical surface area of CuCo₂S₄/Fe₂O₃/CC was 2.76 times larger than that of CuCo₂S₄/CC due to the high double-layer capacitance. For the oxygen evolution reaction, CuCo₂S₄/Fe₂O₃/CC could achieve an overpotential of 273 mV and a Tafel slope of 67 mV dec⁻¹ in alkaline solution.