Nonthermal plasma assisted CO₂ hydrogenation over intermetallic Pd₂Ga/SiO₂

Coupling nonthermal plasma (NTP) with heterogeneous catalysis has been applied in C1 chemistry and is attracting more attention as an alternative to conventional thermal catalysis.^{1, 2} However, the fundamental reaction pathway in NTP-activated CO₂ hydrogenation has not been fully explored and are still not clear. Here, we investigated the NTP-assisted CO₂ hydrogenation in Pd₂Ga/SiO₂ catalyst and compared to thermal catalysis. To gain mechanistic insight between NTP-activated species and intermetallic catalysts, we performed in situ transmission IR spectroscopy. In addition, chemical and structure transition of catalysis during NTP-activated CO₂ hydrogenation were conducted by in situ X-ray absorption fine structure (XAFS) analysis. In situ characterizations indicate that NTP-assisted CO₂ hydrogenation improved compared to thermal catalysis. In particularly, bending mode of vibrationally-excited CO₂ can react with hydrogen adsorbed on the catalyst surface to promote formate formation. This work provides a fundamental mechanism for the interacting NTP-activated species and intermetallic catalysts and sheds light on the rational design of NTP-assisted catalysis.