Photoelectrocatalytic hydrogen generation coupled with reforming of glucose into valuable chemicals using a nanostructured WO3 photoanode

Abstract

Coupling the photo-oxidation of biomass derived substrates with water splitting in a photoelectrochemical (PEC) cell is a broadly discussed approach intended to enhance efficiency of hydrogen generation at the cathode. Here, we report a PEC device employing a nanostructured semitransparent WO3 photoanode that, irradiated with simulated solar light achieves large photocurrents of 6.5 mA cm−2 through oxidation of glucose, a common carbohydrate available in nature that can be obtained by processing waste biomass. The attained photocurrents are in a large part due to the occurrence of the photocurrent doubling, where oxidation of glucose by the photogenerated positive hole is followed by injection by the formed intermediate of an electron into the conduction band of WO3. Selection of an appropriate supporting electrolyte enabled effective reforming of glucose into valuable products: gluconic and glucaric acids, erythrose and arabinose with up to 64% total Faradaic yield attained at ca 15% glucose conversion.

WO3‐based Materials for Photocatalytic and Photoelectrocatalytic Selective Oxidation Reactions

“…[84] In a study by Jakubow-Piotrowska et al, PEC oxidation of glucose into value-added chemicals coupled with H 2 production was achieved using a WO 3 photoanode. [85] A total Faradaic yield of up to 64 % has been achieved in that system for gluconic and glucaric acids, erythrose and arabinose at 15 % glucose conversion in 0.5 NaCl solution. Later, PEC glyoxal oxidation into value-added glyoxylic acid over a crystal facetmodulated WO 3 nanoplate photoanode has been investigated.…”

“…Besides, PEC oxidation using WO 3 as photoanodes has been reported [84] . In a study by Jakubow‐Piotrowska et al., PEC oxidation of glucose into value‐added chemicals coupled with H 2 production was achieved using a WO 3 photoanode [85] . A total Faradaic yield of up to 64 % has been achieved in that system for gluconic and glucaric acids, erythrose and arabinose at 15 % glucose conversion in 0.5 NaCl solution.…”

Sacrifice and valorization of biomass to realize energy exploitation and transformation in a photoelectrochemical way

“…The 2e − oxidation pathway of glucose in this system is a direct transfer of photogenerated holes to the adsorbed organics, followed by the injection of a single-electron reaction intermediate to the CB to form gluconic acid. 42 Pan et al, 43 on the other hand, exploited the NiOOH/α-Fe 2 O 3 photoanode to oxidize glucose to formate (FA), where aldose is the main intermediate in the conversion process (Fig. 5a).…”

Silver-Boosted WO3/CuWO4 Heterojunction Thin Films for Enhanced Photoelectrochemical Water Splitting Efficiency

“…Among them, tungsten trioxide (WO 3 ) has garnered significant interest due to its suitable band gap of around 2.7 eV, high optical absorption, chemical stability, the long hole diffusion length of approximately 150 nm, and high hole mobility of about 10 cm 2 V −1 s −1 . 6,7 Nevertheless, the intrinsic photoactivity and electron−hole separation efficiency of WO 3 are limited, reducing its overall PEC water splitting efficiency.…”

“…In recent decades, considerable endeavors have been focused on the advancement of binary transition-metal-oxide-based photoanodes that can capture visible light, accounting for approximately 45% of the solar spectrum. Among them, tungsten trioxide (WO 3 ) has garnered significant interest due to its suitable band gap of around 2.7 eV, high optical absorption, chemical stability, the long hole diffusion length of approximately 150 nm, and high hole mobility of about 10 cm 2 V –1 s –1 . , Nevertheless, the intrinsic photoactivity and electron–hole separation efficiency of WO 3 are limited, reducing its overall PEC water splitting efficiency. Although binary oxides exhibit commendable stability against photocorrosion and superior photoabsorption capabilities, they still face challenges related to charge transport and separation efficiency .…”