Tuning the electronic structure of bimetallic CoCu clusters for efficient hydrolysis of ammonia borane

Efficient and low cost catalysts for the hydrogen production from ammonia borane (AB) are highly required to build up the upcoming hydrogen economy. Here we demonstrated that the non-active material could be directly transformed to highly active catalyst for the hydrolysis of AB when the surface parts were stripped to form tiny clusters on graphene oxide (GO), with the presence of strong cluster-support interaction. Moreover, the catalytic activity can be greatly enhanced by further tuning the electronic structure of clusters with various compositions. As a result, the final bimetallic CoCu catalyst on GO can achieve a high total turnover frequency (TOF) value of 72.4 (H₂) mol/(Cat-metal) mol·min with an activation energy of 47.8 kJ/mol, which is over 3 times higher than the monometallic clusters on GO. The cluster-support interaction has been clearly identified by synchrotron radiation X-ray absorption spectroscopy. An internal charge transfer from Cu to Co in the clusters can also be identified, which will weaken the B-N bond in AB and then effectively accelerate the hydrolysis of AB to achieve the high performance.