Although solar irradiation has demonstrated beneficial synergy for catalytic CO₂ hydrogenation, it has long been debated as to whether the observed photo-assisted catalytic enhancement has a photo-activation component or is driven solely by the heating effect. Here, we confirm that surface adsorbates play a critical role in photo-assisted CO₂ activation. We isolate the rate-determining intermediate species in the photo-assisted Sabatier reaction by in situ isotopic spectroscopy. Specifically, we reveal that photo-activation of the formate adsorbate (HCO₂*) offers an eightfold photo-enhancement on NiO_x/La₂O₃@TiO₂. Concurrently, the active La₂O₃@TiO₂ support facilitates the adsorption of CO₂, which may contribute to the sustained HCO₂* formation and conversion. The findings are crucial as they provide surface intermediary insights in the design of catalysts for photo-assisted CO₂ conversion. Ultimately, the understanding may unlock the solar-driven hydrogenation catalytic pathway for other reactions involving HCO₂* such as the synthesis of methanol.

尽管太阳辐射已显示出对催化CO ₂氢化有益的协同作用，但对于观察到的光辅助催化增强是否具有光活化成分还是仅由加热效应驱动，一直存在争议。在这里，我们确认表面吸附物在光辅助CO ₂活化中起关键作用。我们通过原位同位素光谱法在光辅助Sabatier反应中确定了决定速率的中间物种。具体而言，我们揭示了甲酸盐吸附物（HCO ₂ *）的光活化在NiO _x / La ₂ O ₃ @TiO ₂上提供了八倍的光增强。同时，活性La ₂O ₃ @TiO ₂载体促进了CO ₂的吸附，这可能有助于持续的HCO ₂ *形成和转化。这些发现至关重要，因为它们为光辅助CO ₂转化催化剂的设计提供了表面中介的见解。最终，该理解可以为涉及HCO ₂ *的其他反应（例如甲醇的合成）开启太阳能驱动的加氢催化途径。