Hydrogen production from complete dehydrogenation of hydrazine borane on carbon-doped TiO2-supported NiCr catalysts

Abstract

Building efficient, durable, and inexpensive catalysts to promote hydrogen production from hydrazine borane (N₂H₄BH₃) is crucial, but it remains a huge challenge. In this work, we report a simple and green wet chemical method to prepare Cr-modified Ni nanoparticles (NPs) immobilized on carbon doped mesoporous TiO₂ (CTO). Three different morphologies (nanosphere (NS), nanoflake (NF), and nanorod (NR)) of CTO were synthesized using ethanol and/or glycerol by the hydrothermal process. It was found that the CTO morphology has a significant impact on the size, dispersion, and electronic structure of Ni–Cr NPs. Clearly, compared with CTO–NS and CTO–NR, CTO–NF-supported Ni–Cr NPs exhibited 100% H₂ selectivity and the best catalytic performance for hydrogen production from N₂H₄BH₃. The turnover frequency (TOF) value of Ni–Cr/CTO–NF reached 555 h⁻¹ at 323 K, which exceeded almost all reported noble-metal-free catalysts. More importantly, the catalytic performance of Ni–Cr/CTO–NF in N₂H₄BH₃ dehydrogenation did not decrease significantly after 20 runs. Its ultra-high catalytic activity and significant durability are attributed to the small electron rich Ni–Cr NPs caused by the unique nanoflake structure of CTO–NF. This work provides ideas for constructing catalysts with different structures and lays the foundation for the development of efficient and cheap hydrogen production catalysts.