Hydrogen Gas Sensing of Co3O4-Decorated WO3 Nanowires

Co3O4 nanoparticle-decorated WO3 nanowires were synthesized by the thermal oxidation of powders followed by a solvothermal process for Co3O4 decoration. The Co3O4 nanoparticle-decorated WO3 nanowire sensor exhibited a stronger and faster electrical response to H-2 gas at 300 degrees C than the pristine WO3 nanowire counterpart. The former showed faster response and recovery than the latter. The pristine and Co3O4-decorated WO3 nanowire sensors showed the strongest response to H-2 gas at 225 and 200 degrees C, respectively. The Co3O4-decorated WO3 nanowire sensor showed selectivity for H-2 gas over other reducing gases. The enhanced sensing performance of the Co3O4-decorated WO3 nanowire sensor was explained by a combination of mechanisms: modulation of the depletion layer width forming at the Co3O4-WO3 interface, modulation of the potential barrier height forming at the interface, high catalytic activity of Co3O4 for the oxidation of 112, active adsorption of oxygen by the Co3O4 nanoparticle surface, and creation of more active adsorption sites by Co3O4 nanoparticles.