A robust sandwich structural catalyst of (Cu/CuCo-MOF)2/MXene double heterojunction with outstanding activity toward hydrogen generation

Non-noble metal catalysts have exhibited promising prospects in ammonia borane (NHBH) hydrolysis, but their activity and stability still need to be further improved. Herein, a 2D sandwich heterostructural catalyst with Cu/CuCo-MOF and MXene-MOF double heterojunction has been prepared by coupling TiCT MXene with bimetal organic framework nanosheets using a facile in situ growth strategy. The optimized CuCo-MOF/MX exhibits unprecedented activity with a turnover frequency (TOF) of 82.3 min and excellent cycle stability, comparable to precious metal catalysts. Spectroscopic characterization and density functional theory (DFT) calculations reveal that Cu/CuCo-MOF heterojunction provides CuCo dual active sites for catalysis, and MXene-MOF heterojunction modulates the electronic structure and valence states of Cu sites via the TiCT interlayer with 2D electron promoter effect to improve the synergistic effect of CuCo dual active sites. These modulation optimize the adsorption and dissociation of reactants, leading to a lower reaction barrier. This work provides insight into the 2D electron promoter effect, proposes a novel strategy for improving the performance of non-precious metal catalysts through constructing double heterojunction with 2D electron promoter effect.