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The potential would be an important issue for enhancing photocatalytic HER and CO 2 photoreduction selectivity. Herein, the Co 3 O 4 /Ti3+-TiO 2 hollow S-scheme heterojunction is fabricated via continuous light modification-chemical-annealing-reduction method. Evaluated by photocatalytic performance, the as-prepared Co 3 O 4 /Ti3+-TiO 2 hollow S-scheme heterojunction exhibits remarkable photocatalytic performance enhancement than single TiO 2 , including hydrogen evolution (∼396.16 μmol/g·h, ∼15 folds) and CO 2 photoreduction (H 2 /CH 4 /CO: ∼20.32/80.57/9.85 μmol/g·h, ∼20 folds), and achieves CO 2 photoreduction to CH 4 selectivity enhancement, which can be mainly ascribed to the synergism of Ti3+/O v and S-scheme heterojunction. There, Ti3+/O v can not only increase the solar efficiency, but also decrease the energy barrier of H+ and ∗CO photoreduction to enhance HER and CO 2 to CH 4 selectivity, including promote the H+ diffusion and CO 2 absorption. Additionally, the formed Co 3 O 4 /Ti3+-TiO 2 S-scheme heterojunction can promote the photo-generated carrier separation/transportation. Also, the hollow 3D structure obtained by ZIF-67 self-template can increase solar efficiency and stability. [Display omitted] • Ti3+/O v can decrease ∗CO photoreduction energy barrier to enhance CH 4 selectivity. • Ti3+/O v with shallow donor level can increase carrier concentration. • Heterojunction can promote carriers separation/transport via appropriate potential. • Hollow 3D structure can increase interface heterojunction and stability. • ZIF-67 self-template can decrease photocatalyst corrosion. [ABSTRACT FROM AUTHOR]

Self-assembled catalyst has the excellent selectivity and activity at low concentrations of CO 2. [Display omitted] • The self-assembled catalyst of CC3/Pd is synthesized. • Catalyst has the excellent selectivity and activity at low concentrations of CO 2. • The size effect of Pd nanoparticles has been systematically studied. • The mechanism of catalyst photoreduction CO 2 to CH 4 is studied. Porous heterogeneous photocatalysts containing both CO 2 adsorption and catalytically active sites can be might beneficial to achieve photoreduction of low concentrations of CO 2 to methane. Here, we show a self-assembled catalyst by combining catalytically-active Pd nanoparticles and porous organic cages for the CO 2 -to-CH 4 photoreduction reaction in the presence a molecular photosensitizer and a sacrificial reagent. The Pd nanoparticles is vital for the high CH 4 selectivity (over 97%) for the CO 2 photoreduction reaction, but they suffer from the low catalytic activity. When these Pd nanoparticles are equipped with an underneath support of porous organic cages, it dramatically boosts the catalytic activity with a high production rate of 78.5 μmol g-1h−1, while the CH 4 selectivity is up to ∼ 98% (electron basis). Importantly, when the photoreduction is performed under low concentration of CO 2 (10% concentration), over 98% of CH 4 selectivity and nearly 50% of the catalytic activity for the Pd-based catalysts retains. [ABSTRACT FROM AUTHOR]

[Display omitted] • Representative studies about CdS-based nanomaterials for the photoreduction of CO 2 are illustrated. • The modification strategies of CdS-based photocatalysts as well as DFT calculation are highlighted. • Perspectives and challenges in this field of photoreduction of CO 2 by CdS-based nanomaterials are presented. Semiconductor-based CO 2 photoreduction for generating chemical energy has recently attracted special attention owing to its tremendous potential for solving increasingly grim energy crises and environmental concerns. Among them, Cadmium sulfide (CdS)-based nanomaterials have attracted enormous attention on account of the relatively narrow band gap for harvesting visible-light and well-suited band position for CO 2 photoreduction. Herein, the comprehensive review focus on the application and progress in CO 2 photoreduction over CdS-based photocatalysts. In this review, we begin with a detailed discussion of CdS materials in CO 2 photoreduction, including fundamental of CO 2 photoreduction as well as products selectivity. In particular, we will highlight the modification of CdS materials for efficient CO 2 photoreduction. And the utilization of density functional theory (DFT) in the study of CO 2 photoreduction over CdS-based photocatalysts is emphasized. Moreover, the remaining challenges to investigate and optimize the catalyzing ability of CdS-based catalysts are stated to indicate possible future development of CdS. [ABSTRACT FROM AUTHOR]