Preparation and high catalytic performance of hollow BN spheres-supported Ni for hydrogen production from methanol

Abstract

In this study, we successfully achieved (1) the preparation of nano-sized hollow boron nitride spheres (HBNS), (2) deposition of nano-sized Ni metal on HBNS (Ni/HBNS) by reduction of Ni(OH)₂-coated HBNS in H₂/Ar, (3) high catalytic performance of Ni/HBNS for H₂ generation by the decomposition of methanol. The phases occurring during processes (1)–(3) were identified by X-ray diffraction. The microstructures of HBNS and Ni(OH)₂- and Ni-deposited HBNS were observed by scanning electron microscopy and transmission electron microscopy, and high-resolution transmission electron microscopy. HBNS were prepared by dissolving the amorphous cores of BN spheres having crystallized shells (core–shell BNS) in hot water. Core–shell BNS were obtained by high-temperature heat treatment in NH₃ of amorphous BN spheres formed from an ammonia borane complex. N₂ adsorption measurements revealed that continuous channels approximately 4 nm wide existed in the shells of HBNS. Ni(OH)₂ films were coated onto HBNS surfaces by immersing core–shell BNS in a hot nickel formate solution. Compared with the conventional Ni-deposited γ-Al₂O₃ catalyst, the Ni/HBNS catalyst exhibited higher selectivity and activity in the generation of H₂ during the decomposition of methanol.