Engineering Coexposed {001} and {101} Facets in Oxygen-Deficient TiO₂ Nanocrystals for Enhanced CO₂ Photoreduction under Visible Light

Abstract

This work for the first time reports engineered oxygen-deficient, blue TiO2 nanocrystals with coexposed {101}-{001} facets (TiO2–x {001}-{101}) to enhance CO2 photoreduction under visible light. The TiO2–x {001}-{101} material demonstrated a relatively high quantum yield (0.31% under UV–vis light and 0.134% under visible light) for CO2 reduction to CO by water vapor and more than 4 times higher visible light activity in comparison with TiO2 with a single {001} plane or {101} plane and TiO2(P25). Possible reasons are the exposure of more active sites (e.g., undercoordinated Ti atoms and oxygen vacancies), the facilitated electron transfer between {001} and {101} planes, and the formation of a new energy state (Ti3+) within the TiO2 band gap to extend the visible light response. An in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study was applied to understand the roles of coexposed {001}-{101} facets and Ti3+ sites in activating surface intermediates. The in situ DRIFTS analysis suggested that the coexposed {001}-{101} facets increased the capacity of reversible CO2 adsorption and that the combination of {001}-{101} and Ti3+ enhanced the activation and conversion kinetics of adsorbed species. The visible light responsive TiO2–x {001}-{101} material is not oxidized after long-term exposure to an air environment. This work is a significant contribution to the design of efficient and stable solar fuel catalysts.

Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

“…The Ti 3+ species are created due to the Ti 4+ reduction of TiO 2 by the treatment with NaBH 4 , so the white TiO 2 nanobelt is turned to black52. NaBH 4 reduction induces a distinctly increase in the peak intensity of Ti 3+ and the result shows that more Ti 3+ is formed on the surface or subsurface of b-TiO 2 , which may change the surface chemical bonding environment of TiO 2 53.…”

Recent progress on advanced design for photoelectrochemical reduction of CO2 to fuels

“…Profiting from the modulation of energy band structure and creation of CUSs, self-doping and defect engineering have received more attention in photocatalytic CO 2 reduction [97,98] and PEC water splitting [99]. However, their application in PEC CO 2 reduction was rarely reported.…”

Katalyse der Kohlenstoffdioxid‐Photoreduktion an Nanoschichten: Grundlagen und Herausforderungen

“…[75,86,87,135] Es wird angenommen, dass Ebenen, die senkrecht zum inneren elektrischen Feld stehen, aktiver in der Photokatalyse sind. [134,138] Bandstrukturen von Photokatalysatoren wie TiO 2 und TMDs hängen stark von der Zusammensetzung und Ordnung der Oberfläche ab.I ndem man die adsorbierten Ionen und Fehlstellen nahe der Oberfläche verändert, passt man die elektronischen Eigenschaften und die Aktivitätd es Photokatalysators an. [137] Verschiedene Oberflächenfacettierungen zeigen auch unterschiedliche Lewis-Aziditätu nd Polarisierungsvermçgen, was wiederum die CO 2 -Adsorption und Aktivierung beeinflusst.…”