Self‐Assembled Urchin‐Like CuWO₄/WO₃ Heterojunction Nanoarrays as Photoanodes for Photoelectrochemical Water Splitting

Abstract

With attractive visible‐light response and chemical stability, CuWO4 has emerged to be a promising candidate as a photoanode for photoelectrochemical (PEC) water oxidation. In this work, we report a one‐step hydrothermal method to prepare CuWO4‐based films directly grown on a conductive glass substrate from a stable precursor solution. By controlling the reaction duration, CuWO4/WO3 heterojunctions with urchin‐like nanoarray morphology are obtained. The CuWO4/WO3 film obtained with an optimized hydrothermal reaction time exhibits an onset potential of 0.6 V and a photocurrent density of 0.48 mA cm−2 at 1.23 V vs. RHE, which is almost five times that of bare CuWO4. The superior structure of the urchin‐like array with large surface area, optimizing film thickness for adequate light absorption and formation of heterojunctions for efficient charge separation conjointly, contributes to the improved performance as well as robust stability.

Block Copolymer Templated WO3 Surface Nanolines as Catalysts for Enhanced Epinephrine Sensing and the Oxygen Evolution Reaction

“…also reported that colloidal WO 3 nanowires for solar water splitting and it is reached 1.96 mA cm −2 at 1.23 V RHE under AM1.5G solar irradiation [47] . WO 3 based materials displayed enhanced photo/catalytic activities due to the increasing charge separation, stability and alleviate photogenerated holes accumulation on the surface [48–52] . Nonetheless, we believe that the overall catalytic activity of WO 3 NLs‐ITO in this study is somewhat limited due to the low content of catalyst on the electrode.…”

“…[47] WO 3 based materials displayed enhanced photo/catalytic activities due to the increasing charge separation, stability and alleviate photogenerated holes accumulation on the surface. [48][49][50][51][52] Nonetheless, we believe that the overall catalytic activity of WO 3 NLs-ITO in this study is somewhat limited due to the low content of catalyst on the electrode. Our future studies will attempt to improve on these results through further fine-tuning of the BCP inclusion process for synthesising thicker and denser (in height and diameter) metal oxide structures.…”

Recent Advances in Self‐Supported Semiconductor Heterojunction Nanoarrays as Efficient Photoanodes for Photoelectrochemical Water Splitting

“…[ 114–118 ] Hybridization of WO 3 with other semiconductors improves the separation of photo‐generated carriers and enhances the visible light absorption response. A variety of semiconductors have been coupled with WO 3 nanoarrays to form heterojunctions as improved photoanodes for water oxidation, including CuO (1.4 eV), [ 119 ] Fe 2 O 3 (2.0–2.2 eV), [ 115,120 ] SbSI (2.0 eV), [ 121 ] ZnIn 2 S 4 (2.0–2.4 eV), [ 122 ] CuWO 4 (2.25–2.45 eV), [ 116,123 ] BiVO 4 (2.4 eV), [ 54,124 ] CdS (2.4 eV) [ 125 ] and C 3 N 4 (2.7 eV). [ 126 ] The activities of some representative WO 3 ‐based heterojunction nanoarrays for PEC water splitting are summarized in Table 3 .…”

Oriented CuWO4 Films for Improved Photoelectrochemical Water Splitting

“…In addition to the increased carrier concentration noted by the above papers, Guo et al ascribed the improvement of PEC performance of CuWO 4 to the reduced activation energy of the water splitting reaction after the formation of oxygen vacancies on the surface of the photoanode . Different from doping and oxygen vacancies, constructing a heterojunction is a strategy for promoting the separation of photogenerated electron and hole pairs by forming a built-in electric field. − The CuWO 4 /BiVO 4 type II heterojunction, CuWO 4 /Mn 3 O 4 p–n junction, and WO 3 /CuWO 4 heterojunction ,,− were constructed, and a built-in electric field is formed because of the difference between the semiconductors. In addition, there are numerous studies to improve charge separation at the interface by loading cocatalysts on the surface.…”