High Refractive Index Dielectric Nanoparticles for Optically-Enhanced Activity of Water-Splitting Photoanodes

Metal oxide semiconductors have shown considerable potential for photoelectrochemical water-splitting. However, no ideal material has emerged which benefit from both an attractive sunlight absorption and efficient charge transport properties. In this work, we show that decorating photoanodes with high refractive index nanoparticles such as amorphous titania can result in reduced reflection losses at the electrolyte/photoanode interface, thereby increasing the performances under illumination from the electrolyte side. A proof of concept is obtained for a bismuth vanadate photoanode including a surface catalyst and a hematite photoanode. The photocurrent density and external quantum efficiency are improved by up to 10% upon nanoparticle decoration, quantitatively matching the decrease in reflectance. Simulations show that a similar enhancement happens when a thick bismuth vanadate photoanode with optimal charge transport properties is considered, thereby suggesting that this strategy can improve photoanodes suffering from high reflection losses regardless of the bare sample performance.

Automated summary

This study investigates the use of high refractive index nanoparticles to reduce reflection losses on photoanodes, thereby improving the performance of photoelectrochemical water-splitting. The results show that nanoparticle decoration on bismuth vanadate and hematite photoanodes leads to a 10% increase in photocurrent density and external quantum efficiency.