Comparison of Boron and Carbon-doping on Molybdenum Substrate via CVD for Hydrogen Evolution Reaction (HER)

In this study, boron (B-Mo) and carbon (C-Mo) were synthesized via chemical vapor deposition (CVD) on bulk molybdenum substrate to investigate the comparative effects of dopant species on material structure and HER performance in acidic media. Structural characterization revealed that C-Mo exhibited amorphous carbon layers with partially disordered graphitic domains, whereas B-Mo formed uniform boron-rich layers with increased surface roughness and porosity. Electrochemical testing in 0.5 M H2SO4 showed that B-Mo achieved a lower overpotential of 439 mV at 10 mA/cm² compared to 456 mV for C-Mo, indicating superior HER activity for boron doping. Tafel slope analysis supported this trend, with B-Mo exhibiting a slope of 296 mV ·dec?¹ and 282 mV·dec?¹ for C-Mo, suggesting almost equivalent kinetics. The relationship between dopant type, surface morphology, and electrochemical behavior was systematically explored to identify the optimal dopant for HER enhancement. This work provides important insights into the rational design of doped molybdenum electrocatalysts and advances the development of cost-effective materials for sustainable hydrogen production.