Electron transport bridges and photothermal synergy at Pd-Ti interfaces for complete-selectivity CO2 conversion to formic acid

Photothermal-driven catalytic conversion of CO 2 into formic acid (HCOOH) offers a promising route for sustainable energy storage and carbon neutrality. However, the efficiency of this process is often limited by sluggish reaction kinetics and rapid charge carrier recombination. This study presents a strategically designed Pd/TiO 2 catalyst—fabricated via impregnation—that enhances CO 2 hydrogenation through improved electron transfer and photothermal synergy. Under simulated solar irradiation (0.15 W·cm −2 ), the optimized 1 wt% Pd/P25 catalyst achieves a CO 2 conversion efficiency of 8.51 % and a solar-to-chemical energy conversion of 7.39 %, with a HCOOH selectivity exceeding 99 %. The HCOOH production rate reaches 25.32 mmol·g cat −1 ·h −1 , representing a 3.5-fold enhancement over pristine TiO 2 . Through in situ spectroscopy and DFT calculations, Pd sites are identified as dual-functional centers for photon absorption and catalytic activation, reducing the activation energy by 19.8 % compared to pure thermal catalysis. Furthermore, the Pd–Ti interface promotes CO 2 chemisorption by stabilizing the *OCHO intermediate (ΔEads = –3.746 eV). This work demonstrates the effective integration of photo- and thermal energy at metal–oxide interfaces to overcome the activity–selectivity trade-off in CO 2 conversion, providing valuable insights for the design of efficient photothermal catalytic systems.