A series of nonprecious metal nanoparticles (NPs) supported by metal-organic framework MIL-101 were synthesized using four methods and their catalytic performance on hydrogen evolution from ammonia borane (NHBH) was studied. The results showed that the crystalline Co NPs with size of 4.5-8.5 and 14.5-24.5 nm had low activities featuring the total turnover frequency (TOF) values of 9.9 and 4.5 mol mol min, respectively. In contrast, the amorphous Co NPs with size of 1.6-2.6 and 13.5-24.5 nm exhibited high activities featuring the total TOF values of 51.4 and 22.3 mol mol min, respectively. The remarkably different activities could be ascribed to the different crystallinity and size of Co NPs in the catalysts. Moreover, the ultrasound-assisted in situ method was also successfully applied to bimetallic systems, and MIL-101-supported amorphous CuCo, FeCo and NiCo NPs had the catalytic activities with total TOF values of 51.7, 50.8, and 44.3 mol mol min, respectively, which were the highest in the values of the reported non-noble metal Co-based catalysts. The present approach, namely, using the synergistic effect of crystallinity and size of metal NPs, may offer a new prospect for high-performance and low-cost nanocatalysts.

Through enriching the electron density of metal nanoparticles, the non-precious catalysts exhibited ultra-high visible-light-driven activities in room-temperature hydrogen evolution from NH3BH3.

Through tuning the functionalized groups in MIL-101, the low-cost catalyst containing NH2 exhibited remarkably high activity in dehydrogenation of HCOOH.

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Through decreasing the size of AuPd nanoparticles, catalytic activity enhancement in hydrogen generation from formic acid was achieved.