A research group headed by Professor In Soo-Il in the Department of Energy Engineering at DGIST has come up with a high-efficiency photocatalyst that has the potential to transform carbon dioxide (CO2), a significant contributor to global warming, into the energy resource methane.
DGIST. Image Credit: Daegu Gyeongbuk Institute of Science and Technology
The research group improved the composition of nanoparticle co-catalysts and ruthenium doping to improve the electrical and optical properties of the photocatalyst. Concurrently, they enhanced the methane conversion efficiency by improving CO2 adsorption via hydroxy surface treatment.
The research group anticipates this technology to be relevant to carbon capture and utilization, thereby making it feasible to regulate the steadily high concentration of atmospheric CO2 while transforming it into methane resources.
In 2022, the global CO2 concentration exceeded 420 ppm, the highest level in 4.1 million years. Unparalleled increases in atmospheric CO2 concentrations have resulted in climate-related disasters across the world, such as 20 billion USD (around 25.4 trillion KRW) in economic losses as a result of droughts in Europe and record-breaking torrential rains on the Korean Peninsula.
To tackle this problem, the concentration of CO2, the cause of climate disasters, must be decreased. The World Economic Forum has determined so-called “solar compounds” that have the potential of transforming CO2, a significant contributor to global warming, into several fuels by making use of solar energy as one of the top ten promising technologies of 2020.
Among the solar compound technologies, photocatalysts that transform highly stable CO2 into fuels like methane utilizing just sunlight and photocatalysts via gas-phase reactions are drawing attention as the main technologies for the future chemical industry, with the goal of decreasing atmospheric CO2 and generating fuel concurrently.
But presently commercialized photocatalysts like P25 have restrictions, like a large bandgap that hinders the absorption of slow charge transfer and visible light.
Numerous studies have made an attempt to resolve these problems. However, difficulties in obtaining high-efficiency photocatalyst development have persisted as a result of inherent issues like low CO2 adsorption and conversion efficiency in gas-phase reactions.
The research group at DGIST, headed by Professor In Soo-Il, came up with a high-efficiency photocatalyst by binding silver nanoparticle co-catalysts to P25 created of titanium dioxide and enhancing charge transfer performance along with ruthenium doping.
Also, they resolved the problem of a low CO2 concentration on the catalyst surface at the time of gas-phase reactions by developing hydroxy groups on the surface of the photocatalyst via hydrogen peroxide treatment.
The research group illustrated that electrons house in an intermediate state of the P25 band structure via ruthenium doping. Such accumulated electrons are further transferred to the silver nanoparticle co-catalyst, thereby transforming CO2 into methane.
The research group also determined the optimal composition to effectively produce methane from CO2 by examining the silver nanoparticle co-catalyst and ruthenium doping. Moreover, by quantifying the amount of adsorbed CO2, the researchers proved that the photocatalyst surface adsorbed more acidic CO2 when it was alkalized with hydrogen peroxide.
The newly developed photocatalyst improves visible light absorption, CO2 adsorption, and electron transfer capabilities simultaneously.
In Soo-Il, Professor, Daegu Gyeongbuk Institute of Science and Technology
Soo-Il added, “It converts 135 times more methane with 95% selectivity compared to the currently commercialized P25 photocatalysts and maintains over 96% stability even after 24 hours of continuous operation. We will conduct follow-up research to improve the stability and selectivity of hydrocarbons for the practical application of this technology.”
This study was performed as part of a medium-term research project that has been sponsored by the Ministry of Science and ICT, and the study outcomes were reported in Carbon Energy, a renowned international journal in the field of energy and the environment.
Journal Reference
Hiragond, C. B., et al. (2023) Surface-modified Ag@Ru-P25 for photocatalytic CO2 conversion with high selectivity over CH4 formation at the solid–gas interface. Carbon Energy. doi.org/10.1002/cey2.386.