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

Abstract

Nanostructured CuWO4 photoanodes were fabricated through a facile electrodeposition method, which was followed by annealing the sample at 500 °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 mW cm−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.

Boosting the Activity and Stability of Copper Tungsten Nanoflakes toward Solar Water Oxidation by Iridium-Cobalt Phosphates Modification

“…70% increase over that of CuWO 4 (0.32 mA•cm −2 ). However, no obvious shift of the OER onset potential is observed, which is also found in other reports on cocatalyst-modified CuWO 4 [26,[39][40][41]. This indicates that the charge-transfer resistance around the onset potential range is quite large and thus even an OER cocatalyst fails to effectively accelerate the charge transfer.…”

“…Note that, in Ref. [40,41], although the authors named the photoanode CuWO 4 , it actually was, as the authors mentioned in the articles, a mixture of WO 3 and CuWO 4 based on the XRD data where unique WO 3 peaks at ca. 33.2 • can be clearly seen.…”

Nanolayered CuWO4 Decoration on Fluorine-Doped SnO2 Inverse Opals for Solar Water Oxidation

“…Therefore, approaches such as the introduction of effective OER electrocatalyst to minimize the energy penalty associated with water oxidation improved the catalytic efficiency and lowered the excessive potential closely related to the interfacial charge transfer. Specifically, nonprecious and abundant electrocatalysts including Mn-phosphate (MnPO), Co-phosphate, and Ni-based electrocatalysts, have been widely used to reveal the remarkable increase in electrocatalytic properties [10]. Bartlett's group reported that the MnPO-based CuWO 4 photoelectrode exhibited improved PEC performance, corresponding to the cathodic shift of the onset potential for water oxidation by ~ 100 mV and a mild increase in photocurrent density, particularly at low applied bias [11].…”

Ultrasonic Spray Pyrolysis‐assisted Fabrication of Ultrathin CuWO4 Films with Improved Photoelectrochemical Performance

“…Enlighten by the above DFT calculation, we assumed that fabrication of ultrathin CuWO 4 film with high crystallization will be favorable for improving the PEC performance. At present, there are many methods to prepare CuWO 4 thin films, such as reactive co-sputtering, [31] electrodeposition" [32,33] and hydrothermal synthesis. [24,34] However, these methods are usually complicated and the thickness of the film can not be well controlled.…”