Selective Photocatalytic Oxidation of Methane to Oxygenates over Cu–W–TiO₂ with Significant Carrier Traps

Abstract

Direct selective methane photooxidation to liquid oxygenates with high productivity and selectivity under mild reaction conditions is highly urgent but remains challenging. Herein, a Cu and W codoped TiO2 (Cu–W–TiO2) photocatalyst was fabricated to enable aerobic oxidation of methane into oxygenates with limited formation of CO2 under ambient temperature. A high oxygenate productivity of 34.5 mmol g–1 with a remarkable selectivity of 97.1% was achieved over the Cu–W–TiO2 photocatalyst. Based on structural characterizations and mechanism studies, it was suggested that the Cu species acted as hole traps, while oxygen vacancies and the W6+-dopant state worked as electron traps. The inhibited recombination of photogenerated carriers contributed to enhanced photocatalytic efficiency. The modulated electronic and band structure promoted the activation of methane and hindered the overoxidation of oxygenates.

Atomically Dispersed Nickel Anchored on a Nitrogen‐Doped Carbon/TiO2Composite for Efficient and Selective Photocatalytic CH4Oxidation to Oxygenates

“…The yield and selectivity of liquid oxygenates of Ni−NC/TiO 2 are higher than those of Ni−NPs/TiO 2 and TiO 2 , demonstrating the superiority of single atom Ni−NC cocatalysts for the photocatalytic CH 4 oxidation. The excellent photocatalytic performance observed over Ni−NC/TiO 2 is comparable to or even outperforms most reported photocatalysts decorated with either noble metal or non‐noble metal cocatalysts under similar experiment conditions (Table S2) [12, 13, 16, 17, 19, 20, 22–25, 38–40] …”

“…The excellent photocatalytic performance observed over NiÀ NC/TiO 2 is comparable to or even outperforms most reported photocatalysts decorated with either noble metal or non-noble metal cocatalysts under similar experiment conditions (Table S2). [12,13,16,17,19,20,[22][23][24][25][38][39][40] Reactions without photocatalyst, without light or replacing CH 4 with Ar did not yield any product. Isotope labelling experiment using 13 CH 4 was performed to elucidate the source of carbon atoms of the products.…”

Effective SrWO4/TiO2 Heterojunction with Enhanced Carriers Separation and Transfer for Photocatalytic Methane Oxidation

“…XRD patterns were performed to characterize different phase composition of various TiO 2 ‐based photocatalysts (Figure 1a). For the pristine TiO 2 sample, the diffraction peaks at 25.4°, 37.8°, 48.1° and 62.8° were matched with anatase TiO 2 , while those at 36.2° and 54.0° were ascribed to rutile TiO 2 [13] . The crystal structure of anatase or rutile TiO 2 was maintained after combining SWO with TiO 2 .…”

“…For the pristine TiO 2 sample, the diffraction peaks at 25.4°, 37.8°, 48.1°and 62.8°were matched with anatase TiO 2 , while those at 36.2°and 54.0°were ascribed to rutile TiO 2 . [13] The crystal structure of anatase or rutile TiO 2 was maintained after combining SWO with TiO 2 . The characterization diffraction peaks at 27.7°, 30.0°, 33.2°, 45.2°, 47.6°, 51.8°, 55.9°, 57.2°and 72.8°were attributed to SWO (Figure S1).…”

Atomically Dispersed Nickel Anchored on a Nitrogen‐Doped Carbon/TiO2Composite for Efficient and Selective Photocatalytic CH4Oxidation to Oxygenates

“…The excellent photocatalytic performance observed over Ni−NC/TiO 2 is comparable to or even outperforms most reported photocatalysts decorated with either noble metal or non‐noble metal cocatalysts under similar experiment conditions (Table S2). [ 12 , 13 , 16 , 17 , 19 , 20 , 22 , 23 , 24 , 25 , 38 , 39 , 40 ]…”