One‐Step Rapid and Scalable Flame Synthesis of Efficient WO₃ Photoanodes for Water Splitting

Abstract

Photoelectrochemical water splitting is a promising approach for the carbon‐free production of hydrogen using sunlight. Here, robust and efficient WO3 photoanodes for water oxidation were synthesized by the scalable one‐step flame synthesis of nanoparticle aerosols and direct gas‐phase deposition. Nanostructured WO3 films with tunable thickness and band gap and controllable porosity were fabricated by controlling the aerosol deposition time, concentration, and temperature. Optimal WO3 films demonstrate superior water oxidation performance, reaching a current density of 0.91 mA at 1.24 V vs. reversible hydrogen electrode (RHE) and an incident photon‐to‐current conversion efficiency (IPCE) of ca. 61 % at 360 nm in 0.1 m H2SO4. Notably, it is found that the excellent performance of these WO3 nanostructures arises from the high in situ restructuring temperature (ca. 1000 °C), which increases oxygen vacancies and decreases charge recombination at the WO3/electrolyte interface. These findings provide a scalable approach for the fabrication of efficient photoelectrodes based on WO3 and other metal oxides for light‐driven water splitting.

High‐Temperature One‐Step Synthesis of Efficient Nanostructured Bismuth Vanadate Photoanodes for Water Oxidation

“…Very recently, direct deposition of flame‐made nanoparticle aerosols has been used to produce mechanically stable hierarchical electrodes for ZnO‐based dye‐sensitized solar cells and efficient WO 3 photoanodes . This high‐temperature self‐assembly approach could also potentially provide a solution to apply a more favorable temperature profile for the synthesis of BiVO 4, besides being a well‐established route for the mass production of numerous nanoparticle commodities such as carbon black, fumed silica, and Degussa P25.…”

Porous Tungsten Oxide: Recent Advances in Design, Synthesis, and Applications

“…Aerosol deposition time, concentration and temperature control the porosity. [22] A synthesis with the right combinations of morphologies allows access to an abundance of channels/pores in WO 3 . Tungsten oxide with cavities and porosity are effective in catalytic reaction because of their surface reactions.…”

Research advances towards large-scale solar hydrogen production from water

“…248,[302][303][304][305][306] Flame spray pyrolysis as an aerosol deposition method is also highly scalable for facile and fast fabrication of various nanostructured (photo)electrodes. [307][308][309][310] A production rate of a few kilograms per hour is achievable using lab-scale burners with tunable specific surface area and catalytic activity of the produced nanomaterials. [311][312] Notably, although the electrocatalysts produced by these industrially viable fabrication techniques demonstrated excellent catalytic activities, 310,313 the photoelectrodes fabricated using them still showed poorer photoactivities than those state-of-the-art photoelectrodes using conventional lab-scale fabrication techniques.…”