Discovery of a self-healing catalyst for the hydrolytic dehydrogenation of ammonia borane

Abstract

Sustainable catalysts based on earth-abundant elements are considered as economical alternatives to precious-metal-bearing catalysts and could be impactful for many applications. Self-healing sustainable catalysts, which in addition to their ‘green’ characteristic can spontaneously repair themselves without the need of applying heat, pressure or electrochemical bias, are particularly desirable for numerous large-scale chemical processes. Herein, we present the discovery of such a catalyst, named SION-X, for the hydrolytic dehydrogenation of ammonia borane (AB, NH₃BH₃). SION-X, with the chemical formula of Cu^II₂[(BO)(OH)₂](OH)₃, is the synthetic form of the mineral Jacquesdietrichite and, following in situ reduction, catalyzes the release of almost all 3 equivalents of hydrogen (H₂) from 1 equivalent of AB. During the reaction, the Cu^II ions in SION-X are reduced to Cu⁰ nanoparticles, and after the reaction, following exposure to air, they are oxidized re-forming SION-X. As a consequence, the catalytic activity of SION-X toward the production of H₂ from AB remains unchanged over many cycles. The self-healing catalysis of SION-X in the absence of any extra energy input gives a new perspective in heterogeneous catalysis for energy-related applications.