CO 2 -to-high value-added chemicals via a photocatalytic route is of interest but strangled by the low efficiency. Herein, a novel Fe-TiO 2-x /TiO 2 S-scheme homojunction was designed and constructed by using a facile surface modification approach whereby oxygen vacancy (OV) and Fe introducing on the TiO 2 nanorod surface. The as-synthesized Fe-TiO 2-x /TiO 2 S-scheme homojunction exhibits positive properties on promoting photocatalytic CO 2 reduction: i) the nanorod structure provides numerous active sites and a radical charge transfer path; ii) the doped Fe and OV not only synergistically enhance light utilization but also promote CO 2 adsorption; iii) the Fe-TiO 2-x /TiO 2 S-scheme homojunction benefits photoexcited charge separation and retains stronger redox capacity. Thanks to those good characters, the Fe-TiO 2-x /TiO 2 homojunction exhibits superior CO 2 reduction performances with optimized CO/CH 4 generation rates of 122/22 μmol g -1 h −1 which exceed those of pure TiO 2 by more than 9.4/7.3 folds and most currently reported catalytic systems. This manuscript develops a facile and universal approach to synthesize well-defined homojunction and may inspire the construction of other more high-efficiency photocatalysts toward CO 2 reduction and beyond.
Wan Si-Jie,Hou Yan-Ting,Wang Wang,Luo Guo-Qiang,Wang Chuan-Bin,Tu Rong,Cao Shao-Wen
Photocatalytic reduction of CO 2 has attracted considerable interest owing to its potential to resolve the energy and environmental problems. Nevertheless, the lack of proficient photocatalysts has restricted the application of solar-driven photocatalytic CO 2 reduction. Herein, we reported an S-scheme heterojunction by combining g-C 3 N 4 with La 3+ and Rh 3+ co-doped SrTiO 3 through the electrostatic self-assembly method for the efficient photocatalytic CO 2 reduction. In comparison with g-C 3 N 4 , the as-prepared CN/LRSTO-30 wt% S-scheme heterojunction not only possesses a broadened visible-light response due to the defect states in La, Rh co-doped SrTiO 3 induced by co-doped La 3+ and Rh 3+ but also has more adsorption sites for the capture and activation of CO 2 molecules. Additionally, separation and transfer efficiency of the photoinduced charge carriers is much enhanced in the CN/LRSTO-30 wt% S-scheme heterojunction via its robust internal electric field, which is firmly demonstrated by in situ irradiation X-ray photoelectron spectroscopy technology. Consequently, the prepared S-scheme heterojunction achieves impressive photocatalytic CO 2 reduction performance with an average CO and CH 4 evolution rate of 4.1–1.8 μmol·g −1 ·h −1 , respectively, which are ~ 1.9 and ~ 22.5-fold higher than those of pure g-C 3 N 4 . This study provides innovative perspectives on the design of creative S-scheme heterojunctions for applications in photocatalytic CO 2 reduction. Graphical abstract
Hou-Yun Yang,Yi-Xuan Wang,Chuan-Shu He,Yuan Qin,Wen-Qiang Li,Wei-Hua Li,Yang Mu
Regulating cathodic interface properties towards highly effective CH 4 production from CO 2 is of great importance for energy storage using microbial electro-synthesis (MES). Herein, the feasibility and mechanism of two typical redox mediators , neutral red (NR) and anthraquinone-2, 6-disulfonate (AQDS), were evaluated for the improvement of CH 4 formation from CO 2 reduction in mixed-culture biocathodes of MESs. Results showed that the CH 4 formation rates of biocathodes after modification with NR and AQDS were 5.8 and 3.5 times higher than that of unaltered cathodes. Moreover, the coulombic efficiency of CH 4 formation improved from 44.27 ± 4.01% of the control cathode to 64.30 ± 4.83% and 62.26 ± 2.87% after modification with NR and AQDS, respectively. Consequently, the energy efficiency of MESs after cathode modification with NR and AQDS increased to 58.33 ± 3.17% and 53.21 ± 4.11% compared to 38.20 ± 3.12% without modification. Such improvements were likely attributed to the enhanced extracellular electron transfer of microbes, the reduction in internal resistances and the enrichment of hydrogenotrophic methanogens in the mixed-culture biocathodes after modification with NR and AQDS. This study provides an alternative strategy to regulate cathodic interface in MESs for renewable energy storage and biomethane production from CO 2 .
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