Synergistic effects of Fe-substitutional-doping and a surface close-contact Fe₂O₃/CeO₂ heterojunction in Fe/CeO₂ for enhanced CH₄ photocatalytic conversion

Abstract

1 : 3 Fe/CeO2-900/6 was prepared to achieve effective CH4 C–H activation and exhibited excellent CH4 photo-conversion performance with a high C1 product yield of 10.56 mmol gcat.−1 h−1.

Deciphering structural evolution of adsorbed ˙OH species on Zr-oxo nodes of UiO-66 to modulate methane hydroxylation

“…Among these structures, although the stable order is Zr oxo -(H 2 O/O 2 ) > Zr oxo -(H 2 O/H 2 O) > Zr oxo -(˙OOH/˙OH) > Zr oxo -(H 2 O 2 /2˙OH), both the adsorbed O 2 and H 2 O are almost inactive for CH 4 conversion. 70,71 Hence, the metastable Zr oxo -(˙OOH/˙OH) of (˙OH) 4 /UiO-66-H is selected as the active center for the further study of CH 4 activation (Fig. 2d), where the optimized Zr–O bond lengths of Zr oxo -˙OOH and Zr oxo -˙OH are 2.093 and 2.107 Å, respectively.…”

“…66 Then another open Zr site can be passivated by the weakly adsorbed O 2 (ref. [67][68][69] 70,71 Hence, the metastable Zr oxo -(cOOH/ cOH) of (cOH) 4 /UiO-66-H is selected as the active center for the further study of CH 4 activation (Fig. 2d), where the optimized Zr-O bond lengths of Zr oxo -cOOH and Zr oxo -cOH are 2.093 and 2.107 Å, respectively.…”

“…S3e-h †). Among these structures, although the stable order is Zr oxo -(H 2 O/O 2 ) > Zr oxo -(H 2 O/H 2 O) > Zr oxo -(cOOH/cOH) > Zr oxo -(H 2 O 2 /2cOH), both the adsorbed O 2 and H 2 O are almost inactive for CH 4 conversion 70,71. Hence, the metastable Zr oxo -(cOOH/ cOH) of (cOH) 4 /UiO-66-H is selected as the active center for the further study of CH 4 activation (Fig.2d), where the optimized Zr-O bond lengths of Zr oxo -cOOH and Zr oxo -cOH are 2.093 and 2.107 Å, respectively.As depicted in Fig.S3i and j, † with up to ve adsorbed cOH, the generated oxygenic species on Zr-oxo nodes of (cOH)5 /UiO-66-H tend to form the more stable structure of Zr oxo -(O 2 /cOH) with two isolated H 2 O instead of Zr oxo -(H 2 O/cOOH) with one isolated H 2 O 2 (Table S1 †).…”

Elevated photooxidation of CH4 to C1 liquid products over an anatase/rutile TiO2 biphase junction

“…6b). 14 Therefore, it was concluded that the A/R heterojunction in P25-800/2, on the one hand, improved carrier separation efficiency via the formed built-in electrode field, but on the other hand, a lowered CH 4 activation barrier via enhanced the CH 4 polarization induced by interfacial oxygen atoms. Moreover, to delineate the reason for the low average reaction rate during the first hour (only CH 3 OOH (2.2586 mmol g −1 h −1 ) and a small amount of HCHO (0.5124 mmol g −1 h −1 ) were detected, and the total C1 yield was calculated to be only 2.77 mmol g −1 h −1 , and the desorption energy ( E d ) needed for various products to dissolve into water from the catalyst surface were calculated using the DFT results.…”

“…12 In contrast, by establishing a Z-scheme heterojunction, not only increased carrier separation efficiency, but also enhanced redox ability, and widened spectral response ranges can be achieved. 13,14 Establishing a heterophase junction using different TiO 2 phases, such as anatase TiO 2 (A-TiO 2 ) and rutile TiO 2 (R-TiO 2 ), is considered to be an efficient method to improve photocatalytic performance. 15…”