Modulating Co-catalyst/Facet Junction for Enhanced Photoelectrochemical Water Splitting

Rational construction of electric field via assembling appropriate co-catalysts on anisotropic facets is of great significance for improving the photogenerated charge separation efficiency. However, this strategy usually gives rise to Fermi-level pinning which is not contributive to the charge separation but deleterious to the photoelectrochemical performance through consuming the measurable photovoltage. Herein, we demonstrate that manganese dioxide electrodeposited on the (111) facet of titanium dioxide nanorods could tremendously boost the catalytic activity of pristine photoanode via a stronger interface electric field and less photovoltage decay compared with the counterpart grown on the (110) facet. A photocurrent density of 1.65 mA·cm^-2 at 1.23 V (vs reversible hydrogen electrode), nearly the theoretical maximum of titanium dioxide, is achieved by the optimum photoanode with an extremely high separation efficiency of 95.15%. This study offers more in-depth insights into the design of carrier separation strategy through loading co-catalysts on different substrate surfaces for more efficient solar energy conversion.