Simple and Low-Cost Synthesis of Ba-Doped CuO Thin Films for Highly Efficient Solar Generation of Hydrogen

Hydrogen gas is an eco-friendly energy source that can be directly converted to electricity using fuel cells. In this work, CuO and Ba-doped CuO thin films were prepared on glass substrates using a simple successive ionic layer adsorption and reaction (SILAR) method for hydrogen production. For pure and doped films, the (-111) plane was the preferred crystallographic orientation. The bandgap of the pure CuO film was tuned from 1.63 to 1.87 eV after incorporating 6% Ba. The average nanoparticle size of the pure CuO film was reduced from similar to 195 to similar to 100 nm and then to 90 nm as the Ba doping ratio was increased from 2 to 4%. The pure and doped CuO films were composed of a random distribution of nanoparticles in an irregular form, as demonstrated by scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDX) patterns demonstrated the high purity of the deposited films and the rise of the Ba atomic % from 0.21 to 0.82 by increasing the doping level to 6%. The 2% Ba-doped CuO films showed a high photocatalytic performance as a photoelectrode for efficient hydrogen generation. The Ba-doped CuO film displayed the best performance for the water-splitting reaction (photocurrent density J = 17 mA/cm(2)) with long-term stability against photocorrosion. The conversion efficiencies incident photon-to-current efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) were 39.6% at 440 nm and 5.75% at 0.41 V, respectively. Consequently, our work introduced an efficient and cost-effective photocathodic material for practical and industrial hydrogen production.