Sacrificial Template Synthesis of Copper Tungstate: Influence of Preparing Conditions on Morphology and Photoactivity

摘要

Morphology-controlled synthesis of ternary transition metal oxides is very important for theirapplication in many fields. As a typical n-type semiconductor ternary oxide, CuWO4 finds applicationin solar water splitting as a photoanode material. In this work, we successfully prepared the CuWO4nanoflakes (NFs), nanoneedles (NNs) and nanoparticles (NPs) films via a thermal solid-state reactionusing different WO3 as sacrificial templates. We systematically investigated the effect of themorphology, size, and crystal type of the WO3 templates on the resulting CuWO4. We found that themorphology and size of WO3 templates and the reaction temperature were crucial factors thatdominated the formation and morphology of CuWO4. The well-crystallized CuWO4 NFs and NPs wereobtained at 550 oC, whereas, the crystalline CuWO4 NNs could be obtained at a much lowertemperature of 475 oC. All the obtained CuWO4 samples exhibited activity and good stability forphotoelectrochemical (PEC) water oxidation. Among the CuWO4 samples, the NFs exhibited thehighest activity, which was attributed to (1) the high light absorption efficiency obtained from theperpendicularly oriented NF structure and (2) the large electron density. This work reveals thedependence of morphology, crystallinity, and photoactivity of CuWO4 on the preparation conditionsduring sacrificial template synthesis.