Artificial photosynthetic reduction of CO₂ into valuable chemicals is one of the most promising approaches to solve the energy crisis and decreasing atmospheric CO₂ emissions. However, the poor selectivity accompanied by the low activity of photocatalysts limits the development of photocatalytic CO₂ reduction. Herein, inspired by the use of oxygen vacancy engineering to promote the adsorption and activation of CO₂ molecules, we introduced oxygen vacancies in the representative barium titanate (BaTiO₃) photocatalyst for photocatalytic CO₂ reduction. We found that oxygen vacancies brought significant differences in the CO₂ photoreduction activity and selectivity of BaTiO₃. The intrinsic BaTiO₃ showed a low photocatalytic activity with the dominant product of CO, whereas BaTiO₃ with oxygen vacancies exhibited a tenfold improvement in photocatalytic activity, with a high selectivity of ~ 90% to CH₄. We propose that the presence of oxygen vacancies promotes CO₂ and H₂O adsorption onto the BaTiO₃ surface and also improves the separation and transfer of photogenerated carriers, thereby boosting the photocatalytic CO₂ reduction to CH₄. This work highlights the essential role of oxygen vacancies in tuning the selectivity of photocatalytic reduction of CO₂ into valuable chemicals.

To alleviate the energy crisis and global warming, photothermal catalysis is an attractive way to efficiently convert CO₂ and renewable H₂ into value-added fuels and chemicals. However, the catalytic performance is usually restricted by the trade-off between the dispersity and light absorption property of metal catalysts. Here we demonstrate a simple SiO₂-protected metal–organic framework pyrolysis strategy to fabricate a new type of integrated photothermal nanoreactor with a comparatively high metal loading, dispersity, and stability. The core-satellite structured Co@SiO₂ exhibits strong sunlight-absorptive ability and excellent catalytic activity in CO₂ hydrogenation, which is ascribed to the functional separation of different sizes of Co nanoparticles. Large-sized plasmonic Co nanoparticles are mainly responsible for the light absorption and conversion to heat (nanoheaters), whereas small-sized Co nanoparticles with high intrinsic activities are responsible for the catalysis (nanoreactors). This study provides a new concept for designing efficient photothermal catalytic materials.

Excess greenhouse gas emissions, primarily carbon dioxide (CO₂), have caused major environmental concerns worldwide. The electroreduction of CO₂ into valuable chemicals using renewable energy is an ecofriendly approach to achieve carbon neutrality. In this regard, copper (Cu) has attracted considerable attention as the only known metallic catalyst available for converting CO₂ to high-value multicarbon (C₂₊) products. The production of C₂₊ involves complicated C–C coupling steps and thus imposes high demands on intermediate regulation. In this review, we discuss multiple strategies for modulating intermediates to facilitate C₂₊ formation on Cu-based catalysts. Furthermore, several sophisticated in situ characterization techniques are outlined for elucidating the mechanism of C–C coupling. Lastly, the challenges and future directions of CO₂ electroreduction to C₂₊ are envisioned.

Carbon dioxide (CO₂) reduction into chemicals or fuels by electrocatalysis can effectively reduce greenhouse gas emissions and alleviate the energy crisis. Currently, CO₂ electrocatalytic reduction (CO₂RR) has been considered as an ideal way to achieve “carbon neutrality.” In CO₂RR, the characteristics and properties of catalysts directly determine the reaction activity and selectivity of the catalytic process. Much attention has been paid to carbon-based catalysts because of their diversity, low cost, high availability, and high throughput. However, electrically neutral carbon atoms have no catalytic activity. Incorporating heteroatoms has become an effective strategy to control the catalytic activity of carbon-based materials. The doped carbon-based catalysts reported at present show excellent catalytic performance and application potential in CO₂RR. Based on the type and quantity of heteroatoms doped into carbon-based catalysts, this review summarizes the performances and catalytic mechanisms of carbon-based materials doped with a single atom (including metal and without metal) and multi atoms (including metal and without metal) in CO₂RR and reveals prospects for developing CO₂ electroreduction in the future.

The interest in CO₂ conversion to value-added chemicals and fuels has increased in recent years as part of strategic efforts to mitigate and use the excessive CO₂ concentration in the atmosphere. Much attention has been given to developing two-dimensional catalytic materials with high-efficiency CO₂ adsorption capability and conversion yield. While several candidates are being investigated, MXenes stand out as one of the most promising catalysts and co-catalysts for CO₂ reduction, given their excellent surface functionalities, unique layered structures, high surface areas, rich active sites, and high chemical stability. This review aims to highlight research progress and recent developments in the application of MXene-based catalysts for CO₂ conversion to value-added chemicals, paying special attention to photoreduction and electroreduction. Furthermore, the underlying photocatalytic and electrocatalytic CO₂ conversion mechanisms are discussed. Finally, we provide an outlook for future research in this field, including photoelectrocatalysis and photothermal CO₂ reduction.