An effective strategy for promoting charge separation by integrating heterojunctions and multiple homojunctions in TiO2 nanorods to enhance photoelectrochemical oxygen evolution

A simple rapid cooling and heating (RCH) treatment was creatively introduced to form gradient Ti3+ self-doping multiple-homojunction in TiO2 nanorods which integrated with g-C3N4 to form heterojunction to facilitate separation and transportation of carriers due to the formation of built-in electric field. The photocurrent density of such a core–shell heterojunction could reach 1.23 mA cm−2 at 1.23 V (vs RHE) under AM 1.5 G illumination without use of any hole scavenger and cocatalysts, which doubles that of the TCN heterojunction (0.64 mA cm−2) and is one of the best values for the similar TiO2/g-C3N4 heterojunction previously reported.