Anchoring of NiCox alloy nanoparticles on nitrogen vacancy-rich carbon nitride nanotubes toward promoting efficiently photocatalytic CO2 conversion into solar fuel†

Anchoring of NiCo_x alloy nanoparticles (NPs) onto nitrogen vacancy-rich carbon nitride nanotubes (NiCo_x/V_N-CNNTs) with porous structure was well designed toward promoting efficiently photocatalytic conversion of CO₂ into solar fuels in the presence of water vapor. NiCo_x/V_N-CNNTs exhibit not only highly efficient generation of CO, but also a significant amount of CH₄, compared to only CO and a trace amount of CH₄ on pristine V_N-CNNTs and single metal-loading V_N-CNNTs. The photoexcited dynamics show that the synergy modulation of the NiCo_x alloy site and vacancy leverage of CNNT is beneficial for efficient separation of photoinduced electron–hole pairs, in favor of the multiple electron-involving reduction pathways for CH₄ formation. Density functional theory simulations validate that the loaded NiCo_x alloy NPs also provide the driving force for accelerating the absorption of CO₂, reducing the free energy of CO₂-to-CH₄ photoreduction, and decreasing desorption energy of the forming CH₄. This work presents a viewpoint to engineer the composition of nanoalloy-based photocatalysts for improved CO₂-to-CH₄ photoreduction.