Metal phthalocyanines as efficient electrocatalysts for acetylene semihydrogenation

Compared to their booming thermocatalytic counterparts, electrocatalytic acetylene semihydrogenation still remain stagnant owing to its low activity and poor selectivity. Here, we first explore metal phthalocyanines (M(Pc)s) featuring a defined metal coordination environment as electrocatalysts for acetylene semihydrogenation. Consequently, CoPc exhibits an ethylene current density of 150.8 mA cm⁻² and a ∼ 96% ethylene faradaic efficiency under a pure acetylene stream. In-situ electrochemical Raman and theoretical calculations demonstrate that CoPc favors acetylene absorption/hydrogenation processes. Even for crude ethylene containing 1 × 10⁴ ppm acetylene, CoPc manifests a ∼ 99.5% acetylene conversion, a high turnover frequency of 4.86 × 10^–3 s⁻¹ and a large space velocity of 2.4 × 10⁵ ml·g_cat^–1·h⁻¹, outperforming those for reported thermocatalysts. This work facilitates the development of electrocatalytic acetylene semihydrogenation and promises alternatives to traditional thermocatalytic processes.