Co-Co 3 O 4 @carbon core–shells derived from metal−organic framework nanocrystals as efficient hydrogen evolution catalysts

Controllable pyrolysis of metal−organic frameworks (MOFs) in confined spaces is a promising strategy for the design and development of advanced functional materials. In this study, Co-Co 3 O 4 @carbon composites were synthesized via pyrolysis of a Co-MOFs@glucose polymer (Co-MOFs@GP) followed by partial oxidation of Co nanoparticles (NPs). The pyrolysis of Co-MOFs@GP generated a core–shell structure composed of carbon shells and Co NPs. The controlled partial oxidation of Co NPs formed Co-Co 3 O 4 heterojunctions confined in carbon shells. Compared with Co-MOFs@GP and Co@carbon- n (Co@C- n ), Co-Co 3 O 4 @carbon- n (Co-Co 3 O 4 @C- n ) exhibited higher catalytic activity during NaBH 4 hydrolysis. Co-Co 3 O 4 @C-II provided a maximum specific H 2 generation rate of 5,360 mL·min −1 ·g Co −1 at room temperature due to synergistic interactions between Co and Co 3 O 4 NPs. The Co NPs also endowed Co-Co 3 O 4 @C- n with the ferromagnetism needed to complete the magnetic momentum transfer process. This assembly-pyrolysis-oxidation strategy may be an efficient method of preparing novel nanocomposites.