Ligand Vacancy Channels in Pillared Inorganic-Organic Hybrids for Electrocatalytic Organic Oxidation with Enzymatic Activities

Abstract

Simultaneously achieving abundant and well-defined active sites with high selectivity has been one of the ultimate goals for heterogeneous catalysis. Herein, we constructed a class of Ni hydroxychloride (NiHC)-based inorganic-organic hybrid electrocatalysts with the inorganic NiHC chains pillared by the bidentate N-N ligands. The precise evacuation of N-N ligands under ultrahigh-vacuum forms ligand vacancies while partially remaining some ligands as structural pillars. The high density of ligand vacancies forms the active vacancy channel with abundant and highly-accessible undercoordinated Ni sites, exhibiting 5–25 fold and 20–400 fold activity enhancement compared to the hybrid pre-catalyst and standard β-Ni(OH)2 for the electrochemical oxidation of 27 different organic substrates. The tunable N-N ligand could also tailor the sizes of the vacancy channels to significantly impact on the adsorption configuration for the unprecedented substrate-dependent reactivities on hydroxide/oxide catalysts. This approach bridges heterogenous and homogeneous catalysis for creating efficient and functional catalysis with enzyme-like properties.