An S-scheme heterointerface-engineered high-performance ternary NiAl-LDH@TiO₂/Ti₃C₂ MXene photocatalytic system for solar-powered CO₂ reduction to produce energy-rich fuels

While there is much potential for photocatalytic CO₂ reduction, poor light absorption and high recombination rates of photogenerated charges limit its effectiveness. To address these challenges, we systematically developed a heterointerface-engineered ternary hybrid photocatalyst comprising NiAl-layered double hydroxide (LDH), titanium dioxide (TiO₂), and titanium carbide (Ti₃C₂) MXene via an in situ growth approach. As a result of the unique combination of these three components, the synthesized ternary NiAl-LDH@TiO₂/Ti₃C₂ photocatalyst demonstrated broad light absorption spanning across the ultraviolet, visible, and near-infrared regions, as well as elevated CO₂ adsorption capacity. In situ-irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses provided compelling evidence for an unconventional S-scheme charge transfer mechanism in the ternary system that effectively separates the charges and suppresses recombination, allowing NiAl-LDH to maintain its strong reducing capacity and TiO₂ to maintain its robust oxidizing capacity. Utilizing the complementary and synergistic properties of these three components (NiAl-LDH, TiO₂, and Ti₃C₂), an optimized ternary NiAl-LDH@TiO₂/Ti₃C₂ photocatalyst with 30 wt% Ti₃C₂ exhibited extraordinary solar-driven CO₂ reduction performance with a remarkable 99 % CO selectivity against competitive H₂ production and a high apparent quantum yield of 0.81 at 365 nm. Additionally, the ternary photocatalyst exhibited excellent stability, maintaining its performance capacity over multiple CO₂ reduction cycles. This work provides a fresh perspective on designing and creating efficient ternary S-scheme photocatalytic systems for solar-driven CO₂ reduction and highlights the potential for energy-rich fuel production.