Thermally Stable N₂-Intercalated WO₃ Photoanodes for Water Oxidation

Abstract

Synthesis of AmmoniumIn a 20-ml vial, 1.00 g (4.00 mmol) of tungstic acid (Alfa Aesar 82118) was suspended in 5.0 ml water at 80 °C under rigorous stirring. After dropwise addition of 3.00 ml (9.9 mmol) of

Optical properties of tungsten trioxide from first-principles calculations

“…Therefore we also examined the modifications of the absorption spectrum of the oxide upon insertion of N 2 , although for computational convenience we considered a concentration higher than in experiments ( We carried out calculations of N 2 in SC WO 3 , with a di-nitrogen concentration of 1N 2 :1WO 3 . The latter is higher than reported experimentally [9] and was chosen for computational convenience, and because we were interested in probing a qualitative effect of N 2 intercalation in WO 3 ). The computed GW-BSE spectrum of N 2 @WO 3 in Fig.…”

“…However its optical gap (3.0 eV [7]) is larger than desired to absorb visible light. Tungsten trioxide (WO 3 ) is another promising oxide for use in photo-electrochemical water-splitting systems [8][9][10][11][12]: it is stable against photocorrosion; its optical gap (2.6-2.7 eV) is smaller than that of TiO 2 and it may absorb sufficient visible light to generate modest photocurrents. Furthermore WO 3 electrochromism has additional applications, in e.g.…”

“…Our computed absorption spectrum for simple cubic WO 3 agrees well with recent measurements on blue bronze [35], over a wide energy range. In addition to the pure oxide, we also considered di-nitrogen doping, which was shown [9,10] to lower the band gap towards the visible range and thus to be beneficial for solar applications.…”

Mixed‐Metal Tungsten Oxide Photoanode Materials Made by Pulsed‐Laser in Liquids Synthesis

“…[13] A recent report showed that a thin tungsten oxide overlayer with dual oxygen and tungsten vacancies on mesoporous WO3 photoanodes improved photocurrents by a factor of 2.4 due to better interfacial charge transfer and conductivity. [14] Tungsten oxide has been extensively studied theoretically.…”

High pressure resonant X-ray emission studies of WO3 and hydrogenated WO3

“…The goal here entailed adding a dopant into the WO3 lattice with the aim of modifying electronic energy levels via intercalation stress which lowered the 2.6 eV band gap of WO3 to 1.9 eV to improve solar light collection efficiency [1]. As high temperature can cause the loss of intercalated dopants via thermal migration out of the unit cell, we sought to examine the possibility of using an alternative method to dope semiconductors to stimulate intercalation and/or chemical reaction with WO3 that does not add heat : useful hard x-ray photochemistry [2][3][4][5].…”