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The roles of unforgiving H 2 SO 4 solvent in CH 4 activation with molecular catalysts have not been experimentally well-illustrated despite computational predictions. Here, we provide experimental evidence that metal-bound bisulfate ligand introduced by H 2 SO 4 solvent is redox-active in vanadium-based electrocatalytic CH 4 activation discovered recently. Replacing one of the two terminal bisulfate ligands with redox-inert dihydrogen phosphate in the pre-catalyst vanadium (V)-oxo dimer completely quenches its activity towards CH 4 , which may inspire environmentally benign catalysis with minimal use of H 2 SO 4 . 

Abstract The undesirable loss of methane (CH₄) at remote locations welcomes approaches that ambiently functionalize CH₄on‐site without intense infrastructure investment. Recently, we found that electrochemical oxidation of vanadium(V)‐oxo with bisulfate ligand leads to CH₄activation at ambient conditions. The key question is whether such an observation is a one‐off coincidence or a general strategy for electrocatalyst design. Here, a general scheme of electrocatalytic CH₄activation with d⁰early transition metals is established. The pre‐catalysts’ molecular structure, electrocatalytic kinetics, and mechanism were detailed for titanium (IV), vanadium (V), and chromium (VI) species as model systems. After a turnover‐limiting one‐electron electrochemical oxidation, the yielded ligand‐centered cation radicals activate CH₄with low activation energy and high selectivity. The reactivities are universal among early transition metals from Period 4 to 6, and the reactivities trend for different early transition metals correlate with their d orbital energies across periodic table. Our results offer new chemical insights towards developing advanced ambient electrocatalysts of natural gas.