Lattice energy transfer from homo-crystalline substitution for enhanced piezo-photocatalytic CO2 conversion

• La 3+ and Al 3+ double-site homo-crystalline substitution of Sr 2+ with Ti 4+ in SrTiO 3 constructs an electron transport platform. • Introducing a piezoelectrically polarised electric field, coupled photocatalysis further drives the transport of photogenerated electrons. • Theoretical calculations show that CO 2 can spontaneously adsorb on the surface while reducing the desorption energy barrier. The rapid recombination of carriers and large activation energy of CO 2 compromise the efficiency of CO 2 photoreduction. Herein, SrTiO 3 (STO) with different molar ratios of La 3+ and Al 3+ double-site homo-crystalline substitution is prepared by a ball-milling molten salt method. The concentration of Ti 3+ and excess oxygen vacancies decrease to improve the catalytic activity. Meanwhile, the double sites act as electron transfer platforms for easy electron transfer from the bulk phase to the surface to foster CO 2 photoreduction. Not only that, the energy transfer due to doping-induced lattice distortion can potentially enhance the photocatalytic activity. A piezoelectrically polarized electric field is introduced to further expedite charge transport. As a result, the activity of La, Al-STO piezo-photocatalytic CO 2 reduction is improved to 39.17 µmol g -1 h −1 , which is more than seven times better than that of the pure STO. Furthermore, CO 2 adsorbs spontaneously on the catalysts because the thermodynamic energy barrier decreases due to the piezoelectric force, which is verified by density-functional theory calculation. This study reveals the great potential of double-site homo-crystalline substitution of STO pertaining to the charge transport kinetics and thermodynamics of the catalytic reaction in the piezo-photocatalytic CO 2 process.