High-Efficiency Hydrogen Evolution via Water Splitting on Ultrathin 2D TiO₂ Nanosheets

Developing efficient photocatalysts for hydrogen evolution via water splitting remains a major challenge. Herein, ultrathin two-dimensional TiO₂ nanosheets (∼4.5 nm) were synthesized using the triblock copolymer PEO-PPO-PEO (P123) as a structure-directing agent, followed by platinum nanoparticle deposition. The resulting Pt/2D TiO₂ catalyst exhibited an outstanding hydrogen evolution rate of 106.5 mmol g_catal.^-1 h^-1 and a high quantum efficiency of 66% under a 365 nm irradiation. Mechanistic studies revealed that hydrogen production predominantly occurred via water splitting rather than methanol oxidation, with a kinetic isotope effect of 2.5 confirming water decomposition as the rate-determining step. The ultrathin nanosheets shortened the photogenerated carrier migration distance, resulting in enhanced charge separation, evidenced by a photocurrent increase and extended carrier lifetime (2.28 ns). This work provides valuable insights into the design of ultrathin nanosheet-based materials for high-efficiency photocatalytic hydrogen evolution.