Efficient solar-driven CO₂-to-fuel conversion via Ni/MgAlO_x@SiO₂ nanocomposites at low temperature

Solar-driven CO₂-to-fuel conversion assisted by another major greenhouse gas CH₄ is promising to concurrently tackle energy shortage and global warming problems. However, current techniques still suffer from drawbacks of low efficiency, poor stability, and low selectivity. Here, a novel nanocomposite composed of interconnected Ni/MgAlO_x nanoflakes grown on SiO₂ particles with excellent spatial confinement of active sites is proposed for direct solar-driven CO₂-to-fuel conversion. An ultrahigh light-to-fuel efficiency up to 35.7%, high production rates of H₂ (136.6 mmol min⁻¹g⁻¹) and CO (148.2 mmol min⁻¹g⁻¹), excellent selectivity (H₂/CO ratio of 0.92), and good stability are reported simultaneously. These outstanding performances are attributed to strong metal-support interactions, improved CO₂ absorption and activation, and decreased apparent activation energy under direct light illumination. MgAlO_x@SiO₂ support helps to lower the activation energy of CH* oxidation to CHO* and improve the dissociation of CH₄ to CH₃* as confirmed by DFT calculations. Moreover, the lattice oxygen of MgAlO_x participates in the reaction and contributes to the removal of carbon deposition. This work provides promising routes for the conversion of greenhouse gasses into industrially valuable syngas with high efficiency, high selectivity, and benign sustainability.