Investigation of transition metal doping on catalytic activity of Co3O4 catalysts in hydrogen generation from NaBH4 hydrolysis

Hydrogen production from NaBH 4 hydrolysis is a promising approach to on-site H₂ supply, but its practical use is constrained by insufficient catalytic activity and stability of current catalysts. Here Co 3 O 4 catalysts doped with different transition metal ions (W, Ni, Cu and Mo) were prepared via a combined citric-EDTA acid complexation and applied for H 2 generation via NaBH 4 hydrolysis. Effects of various transition metal ions on crystal structure, surface morphologies, and catalytic performance of Co 3 O 4 catalysts were systematically investigated. It can be found that minor doping of transition metal ions does not change the bulk spinel structure of Co 3 O 4 catalysts but can obviously impact its crystallinity and surface morphologies. Moreover, Co 3 O 4 catalysts exhibit distinct induction periods before reaching maximum catalytic activity, with the duration dependent on the type of metal dopants. Notably, Ni-doped Co 3 O 4 catalysts exhibit the highest catalytic activity of 2320   mL·min -1 ·g -1 and a relatively low activation energy of about 25.27   kJ·mol -1 . By contrast, Cu doping exerts a negative effect on the stability of pristine Co 3 O 4 . The catalytic performance follows the order Ni > Mo > W > Cu, with Cu‑doped Co 3 O 4 showing a significantly degraded activity of only 1380.4   mL·min -1 ·g -1 . Meanwhile, an excessively high doping content results in decreased catalytic activity for all samples. This work clarifies the correlation between transition metal doping and Co 3 O 4 optimization, offering theoretical guidance for rational design of high-performance NaBH 4 hydrolysis catalysts.