Significant Enhancement of the Photoelectrochemical Activity of CuWO4 by using a Cobalt Phosphate Nanoscale Thin Film

Nanostructured CuWO4 photoanodes were fabricated through a facile electrodeposition method, which was followed by annealing the sample at 500 degrees C for 2 h. The morphologies, crystalline structure, electronic states, optical behaviors, and photoelectrochemical characteristics of the CuWO4 nanomaterial were examined by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV/Vis spectroscopy, and impedance spectroscopy, showing that the formed triclinic CuWO4 nanoparticles had an indirect band gap of 2.2 eV and strong response to visible light. The cobalt phosphate (CoPi) nanoscale thin film, which was used as a co-catalyst, was electrodeposited on the CuWO4 surface. The photocurrent of the cobalt phosphate complex-catalyzed CuWO4 electrodes exhibited an 86% higher photocurrent response than that of the unmodified CuWO4 nanoparticles under the irradiation of one simulated sun (100 mWcm(-2)). The kinetics of this photoelectrochemical water splitting process was further investigated, and it was found that a more negative flat band potential and reduced charge transfer resistance were likely the primary reasons behind the enhancement.