Coffee ground derived biochar embedded O-NiCoO nanoparticles for efficiently catalyzing a boron‑hydrogen bond break.

The catalytic boron‑hydrogen bond break is usually regarded as an important reaction both in the area of environment treatment and hydrogen energy, attracting increasing attention in the past decades. Due to the limitation of conventional noble metal-based catalyst, cost-effective transition metal-based catalysts with high activity have been recently developed to become the promising candidates. Herein, the coffee ground waste was utilized as the biochar substrate loaded with ultrafine NiCoO nanoparticles. The abundant function groups on the biochar substrate efficiently adsorbed the metal ions and confined the crystal growth spatially, making the NiCoO nanoparticles highly dispersed on the surface. Moreover, the oxygen vacancies were further created in the catalysts by a vacuum-calcination strategy to boost their catalytic activity towards boron‑hydrogen bond break both in the systems of 4-nitrophenol reduction by NaBH and hydrogen release from NHBH. The results indicated that the moderate presence of oxygen vacancies could effectively accelerate the boron‑hydrogen bond break and the catalytic activity performed a satisfied stability during several recycles. The theoretical calculation method was adopted to analysis and discuss the mechanism within this process. This design strategy on active catalysts not only offered a novel solution of biowaste resource reuse but also demonstrated the significant role of oxygen vacancies in energy and environmental catalysis.