Black Titanium Oxide/Activated TaS ₂ Flakes Photoelectrode for Plasmon Assisted Hydrogen Evolution at Neutral pH at High Current Density

Abstract A heterojunction photo‐electrode(s) consisting of porous black titanium oxide (bTiO ₂ ) and electrochemically self‐activated TaS ₂ flakes is proposed and utilized for hydrogen evolution reaction (HER). The self‐activated TaS ₂ flakes provide abundant catalytic sites for HER and the porous bTiO ₂ , prepared by electrochemical anodization and subsequent reduction serves as an efficient light absorber, providing electrons for HER. Additionally, Au nanostructures are introduced between bTiO ₂ and TaS ₂ to facilitate the charge transfer and plasmon‐triggering ability of the structure created. After structure optimization, high HER catalytic activity at acidic pH and excellent HER activity at neutral pH are achieved at high current densities. In particular, with the utilization of bTiO ₂ @TaS ₂ photoelectrode (neutral electrolyte, sunlight illumination) current densities of 250 and 500 mA cm ⁻² are achieved at overpotentials of 433, and 689 mV, respectively, both exceeding the “benchmark” Pt. The addition of gold nanostructures further reduces the overpotential to 360 and 543 mV at 250 and 500 mA cm ⁻² , respectively. The stability of the prepared electrodes is investigated and found to be satisfying within 24 h of performance at high current densities. The proposed system offers an excellent potential alternative to Pt for the development of green hydrogen production on an industrial scale.