Researchers have created an innovative approach using selective, tiny cocatalysts to effectively split water and produce hydrogen, which is a clean fuel option.
In the urgent quest for clean energy alternatives like hydrogen to achieve carbon neutrality, a team from Tohoku University, Tokyo University of Science, and Mitsubishi Materials Corporation has made significant progress in enhancing the efficiency of the photocatalytic process that separates water into hydrogen.
“Water-splitting photocatalysts can generate hydrogen (H2) solely using sunlight and water,” states Professor Yuichi Negishi, the lead researcher from Tohoku University. “Yet, the current methods are not optimized enough for real-world use. By enhancing this activity, we can utilize hydrogen to pave the way for a future energy society.”
The research team has devised a new method that employs ultrafine rhodium (Rh)-chromium (Cr) mixed-oxide (Rh2-xCrxO3) cocatalysts—with a particle size around 1 nm. These are strategically loaded onto specific crystal facets of a photocatalyst (which uses sunlight and water to accelerate reactions). Previous attempts have been unsuccessful in achieving these two objectives together—creating tiny cocatalysts that can be applied to specific areas of the photocatalyst.
A smaller particle size is crucial because it significantly boosts the activity per unit of loaded cocatalyst due to the increased specific surface area. Moreover, selective loading is essential; if the cocatalysts are placed randomly, they may land on parts of the crystal where the desired reaction cannot take place.
The research analyzed the particle size, loading position, and electronic state of the cocatalyst in the photocatalyst obtained through the new F-NCD method (Rh2-xCrxO3/18-STO (F-NCD)) and compared it with that prepared using traditional techniques. Overall, the photocatalysts created with the novel approach demonstrated 2.6 times greater photocatalytic activity in water-splitting. This innovative photocatalyst has achieved the highest apparent quantum yield recorded to date for strontium titanate.
This outstanding technique has enhanced our capability to produce hydrogen without generating harmful byproducts like carbon dioxide. This advancement could enable us to utilize hydrogen as a more plentiful, eco-friendly energy resource, contributing to a healthier environment for everyone.
