Electrochemical CO 2 conversion to chemical products is a promising strategy for sustainable industrial development. However, the success of this approach requires an in-depth understanding of catalysis because it involves highly complex multistep reactions. Herein, we suggest a rational design of a hierarchical Bi dendrite catalyst for an efficient conversion of CO 2 to formate. A high selectivity (∼89% at −0.74 V RHE ) and, more importantly, a stable performance during long-term operation (∼12 h) were achieved with the Bi dendrite. Density functional theory (DFT) is used to investigate three possible reaction pathways in terms of surface intermediate, and the one via *OCOH surface intermediate is calculated to be the most energetically feasible. DFT calculations further elucidate the plane-dependent catalytic activity and conclude that the high-index planes developed on the Bi dendrite are responsible for the sustainable performance of Bi dendrite. We expect that our experimental and theoretical study will provide a fundamental guideline for the CO 2 -to-formate conversion pathway as well as design principles for enhancing the catalytic performance.

Electrochemical reduction of CO 2 into C1 products with high energy density has attracted attention due to the demands for renewable energy sources. Herein, we demonstrate a selective electrocatalytic CO 2 reduction system where the cathode consists of hierarchically structured Au islands catalysts. To be more specific, the Au islands were prepared by oxygen plasma treatment on the Au foil, to increase the current density for the selective production of carbon monoxide with over 95% of faradaic efficiency. Faradaic efficiency, production rate, and the onset potential for CO 2 reduction were significantly improved by the expanded surface area, compared with a polycrystalline Au electrode. Furthermore, the performance of CO 2 reduction to CO was enhanced by adding ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) which has high CO 2 -capture ability and catalytic activity. On the other hand, the rate-determining step of the Au electrode for the CO production determined by Tafel plots was found to be consistent with the initial one electron transfer step to form the surface adsorbed CO 2• -intermediates regardless of the application of hierarchically structured catalyst and ionic liquid in the CO 2 reduction system.

No abstract

No abstract

3D TiO2 photoanodes in dye-sensitized solar cells (DSCs) are fabricated by the soft lithographic technique for efficient light trapping. An extended strategy to the construction of randomized pyramid structure is developed by the conventional wet-etching of a silicon wafer for low-cost fabrication. Moreover, the futher enhancement of light absorption resulting in photocurrent increase is achieved by combining the 3D photoanode with a conventional scattering layer.