Exploring the Size Effect of Pt Nanoparticles on the Photocatalytic Nonoxidative Coupling of Methane

Abstract

The high inertness of the C−H bond makes the photocatalytic methane conversion a significant challenge. The platinum nanoparticle is a promising cocatalyst for CH 4 activation, while the study of its structure characteristics and functionality remains in its infancy. Herein, the size effect of Pt on the photocatalytic nonoxidative methane conversion efficiency was systematically investigated over x-Pt/Ga 2 O 3 with the particle size (x) ranging from 1.5 to 2.7 nm, where a volcano-shaped relation was observed. The smaller size is beneficial to the formation of Pt δ+ species, which is mainly distributed on the terrace sites according to the DFT calculation. The corner Pt atom is the geometric active site for the CH 4 polarization, and the terrace Pt δ+ helps promote C−H activation since the activity is decreased on reduced x-Pt/ Ga 2 O 3 with a lower Pt δ+ content. Meanwhile, Pt δ+ species favors the oxidation of adsorbed −CH 3 group to •CH 3 . The volcanoshaped size effect on the NOCM activity was finally rationalized by the balance between C−H activation and C 2 H 6 desorption from the corner sites on different sized Pt.

Advances and Challenges of Photocatalytic Methane C—C Coupling

“…Immobilization of noble metals on β ‐phase Ga 2 O 3 promotes the activity of Ga 2 O 3 for photocatalytic NOCM. [ 42,44,51 ] For example, the Pd 0.5 /Ga 2 O 3 photocatalyst exhibits the constant formation of ethane and hydrogen with a production rate of 0.22 μmol·h −1 and 0.23 μmol·h −1 , respectively. The generation rate of ethane is more than three times higher than that with the pure Ga 2 O 3 (0.073 μmol·h −1 ).…”

Promises and Challenges in Photocatalysis

“…Today, photocatalytic technology has been mainly applied in the treatment of the industrial wastewater, including papermaking, printing, dyeing and electroplating industry, etc. As for other photocatalysis research fields, such as solar water splitting (Mi et al, 2021), photocatalytic CO 2 reduction (He et al, 2019), photocatalytic CH 4 activation (Ma et al, 2021), nitrogen fixation , and photocatalytic fine chemicals synthesis (Leng et al, 2020;Tan et al, 2021), they often stuck at the proof-of-concept level.…”

Design of Frustrated Lewis Pair in Defective TiO2 for Photocatalytic Non-Oxidative Methane Coupling

“…Photocatalytic non-oxidative coupling of methane (NOCM) is one of the effective approaches to selectively producing ethane and hydrogen under mild conditions [4][5][6][7] . Our previous work has veri ed that Pt δ+ -Pt pair loaded on TiO 2 can promote the photocatalytic C-H polarization at room temperature 5,8 .…”