A triple tandem reaction for the upcycling of products from poorly selective CO₂ photoreduction systems

Low-selective CO₂ photoreduction systems are often overlooked in research, because the resulting mixed products are difficult to use in further reactions. In particular, the reutilization of gaseous hybrid products (such as CO and H₂), which are often mixed with incompletely converted CO₂, is difficult. Here we design and construct two highly active cluster-based catalysts, Ni₅W₁₀ and Ni₆W₁₀, which can be utilized in an efficient triple tandem reaction composed of low-selective CO₂ photoreduction, alkyne semi-hydrogenation and carbonylation reactions. The triple tandem system can sequentially convert the H₂ and CO mixture into high-value olefins and carbonyls, with an atomic utilization efficiency of up to 94%. In situ one-pot coupling of low-selective CO₂ photoreduction with alkyne semi-hydrogenation promotes the overall photoconversion efficiency (up to 1,425.0 μmol g⁻¹ h⁻¹), CO selectivity (from 50.8% to 80.0%) and alkyne-to-olefin transformation (conversion >86.0%, selectivity ~100.0%). Subsequently, the purified CO can be converted to different types of carbonylated product (CO conversion between 51% and 99%).