Enhancing optical phonon energies and persistent yield production of CO via substitutional doping in indium oxide

We report on photo-related effects from doping for the reverse water gas shift reaction: enhanced photo-thermalization, and persistent CO yield post illumination generating a 'memory' effect. Bismuth substitution doping of Indium in Biz-In2O3-x(OH)(y) material systems results in significantly increased CO rate with increasing photo-intensities. Urbach analysis reveals that optical-phonon energies in doped systems increase compared to undoped systems by a factor of 1.18-1.41 in CO2+H-2 atmosphere, suggesting enhanced photo-thermalization at high photo-intensities. Persistent CO yield post photo-illumination for high-doped In2O3-x(OH)(y) has a persistent period of 60 min in flow reactor with decay constant of 24.3 h in batch reactor, enhancing yield by 78% and 17%; low-doped and undoped systems present shorter prolonged production times with 30-40 min in flow reactor with longer decay constant of 31.0-31.5 hours in batch reactor. Linked to slow photocurrent decay trends which extends for 1-2 hours in undoped system, and more than 2 h for high doped system.

Automated summary

The study shows that doping with bismuth as a substitution of indium can significantly increase the CO production rate in the reverse water gas shift reaction under illumination, enhancing the photo-thermalization effect. High-doped In2O3-x(OH)(y) materials exhibit a longer persistent CO yield post-illumination, with increased yield, while low-doped and undoped systems have shorter duration and lower yield. Additionally, undoped systems show a slower decay trend in photocurrent for 1-2 hours, while high-doped systems exhibit a decay trend of more than 2 hours.