Modulation of Excitonic Confinement of TiO2 in Molten Salts for Overall CO2 Photoreduction†

Comprehensive Summary Excitonic confinement greatly determines the charge carrier transport of photocatalysts. A molten salt modulation of excitonic confinement is herein demonstrated as formation of ultrafine carbon‐doped anatase TiO 2 with grafted graphitic carbon nitride, which is rationalized as an excellent catalyst for overall CO 2 photoreduction. Compared with bulk TiO 2 , the carbon‐doped TiO 2 (M‐TiO 2 ) possesses a weaker excitonic confinement to decrease exciton binding energy from 99 to 58 meV, consequently enhancing free‐charge‐carrier generation and transportation. Effective Z‐scheme electron transfer from M‐TiO 2 to C 3 N 4 is built, enhancing the CO 2 conversion via the synchronous optimization of redox ability, CO 2 activation, and *COOH generation. This work highlights the unique chemistry of excitonic dissociation on facilitating separation of electron and hole, and also extends the scope of molten salt‐mediated modulation of photocatalysis materials.