Improved hydrogen generation via NaBH4 hydrolysis: Synergistic role of sulfur and C4+-Doping unveils (440) high-index facets and modulates Co2+/Co3+ ratios in the Co3O4 lattice

Sodium borohydride (NaBH4) is crucial for eco-friendly "green" hydrogen (H2) storage, employing controlled release through catalyzed NaBH4 hydrolysis, mitigating its inherent sluggish self-hydrolysis. Precious metal catalysts enhance this process, but face scarcity and cost issues hindering widespread use, prompting interest in Co3O4, specifically with (311) orientation for abundant Co2+ sites. However, excess Co2+ on dominant (311) facets limits catalytic efficacy. This study presents a nuanced synthesis of sulfur (S)- and carbon (C4+)-doped Co3O4 that expose high-index (440) facets and optimize Co2+/Co3+ distribution. The catalytic performance of CoSC-0.1-700 on (440) facets demonstrates remarkable hydrogen generation rate of 4.1 L g−1. min−1 within 10.5 min, 1.81×, 2.42×, and 3.83× higher than control samples, and undoped Co3O4 with (311) dominance, and 1.24× higher than (220). An estimated activation energy (Ea) of 33.63 kJ mol−1, comparable to noble metals, indicates high performance and stability over ten (10) cycles. This approach promises sustainable future in "green" H2 production.