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Electrochemical water splitting offers the potential for environmentally friendly hydrogen and oxygen gas generation. 

A cobalt porphyrin molecule, namely CoTcPP (TcPP = the dianion of meso -tetra(4-carboxyphenyl)porphyrin), is intercalated into zirconium phosphate (ZrP) layers as an effective way to heterogenize a porphyrin-based molecular electrocatalyst. Fourier-transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRPD) measurements, UV-Vis spectroscopy, elemental mapping, energy dispersive X-ray (EDX) analysis, inductively coupled plasma mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS) were utilized to determine the successful intercalation of CoTcPP into ZrP. While the CoTcPP molecule is not amendable to be used as a heterogeneous catalyst in basic environment due to the carboxylic groups, the intercalated species (CoTcPP/ZrP) is effective towards water oxidation from KOH aqueous solution when utilized as a heterogeneous electrocatalyst and shows remarkable catalytic durability. Electrochemical results show that CoTcPP/ZrP requires an overpotential of 0.467 V to achieve a current density of 10 mA cm −2 while the pristine α-ZrP shows negligible electrocatalytic OER behavior. 

Abstract The enhanced safety, superior energy, and power density of rechargeable metal‐air batteries make them ideal energy storage systems for application in energy grids and electric vehicles. However, the absence of a cost‐effective and stable bifunctional catalyst that can replace expensive platinum (Pt)‐based catalyst to promote oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode hinders their broader adaptation. Here, it is demonstrated that Tin (Sn) doped β‐gallium oxide (β‐Ga₂O₃) in the bulk form can efficiently catalyze ORR and OER and, hence, be applied as the cathode in Zn‐air batteries. The Sn‐doped β‐Ga₂O₃sample with 15% Sn (Sn_x=0.15‐Ga₂O₃) displayed exceptional catalytic activity for a bulk, non‐noble metal‐based catalyst. When used as a cathode, the excellent electrocatalytic bifunctional activity of Sn_x=0.15‐Ga₂O₃leads to a prototype Zn‐air battery with a high‐power density of 138 mW cm⁻²and improved cycling stability compared to devices with benchmark Pt‐based cathode. The combined experimental and theoretical exploration revealed that the Lewis acid sites in β‐Ga₂O₃aid in regulating the electron density distribution on the Sn‐doped sites, optimize the adsorption energies of reaction intermediates, and facilitate the formation of critical reaction intermediate (O*), leading to enhanced electrocatalytic activity.