Although significant research efforts have focused on the exploration of catalysts for the electrochemical reduction of CO2 , considerably fewer reports have described how support materials for these catalysts affect their performance, which includes their ability to reduce the overpotential, and/or to increase the catalyst utilization and selectivity. Here Ag nanoparticles supported on carbon black (Ag/C) and on titanium dioxide (Ag/TiO2 ) were synthesized. In a flow reactor, 40 wt % Ag/TiO2 exhibited a twofold higher current density for CO production than 40 wt % Ag/C. Faradaic efficiencies of the 40 wt % Ag/TiO2 catalyst exceeded 90 % with a partial current density for CO of 101 mA cm(-2) ; similar to the performance of unsupported Ag nanoparticle catalysts (AgNP) but at a 2.5 times lower Ag loading. A mass activity as high as 2700 mA mgAg (-1)  cm(-2) was achieved. In cyclic voltammetry tests in a three-electrode cell, Ag/TiO2 exhibited a lower overpotential for CO2 reduction than AgNP, which, together with other data, suggests that TiO2 stabilizes the intermediate and serves as redox electron carrier to assist CO2 reduction while Ag assists in the formation of the final product, CO.

The electroreduction of CO 2 to CO or other products is one approach to curb the rise in atmospheric CO 2 levels and/or to store excess energy of renewable intermittent sources like solar and wind. To date most efforts have focused on improving cathode catalysis, despite other components such as the anode (oxygen evolution reaction, OER) also being of key importance. Here, we report that the dihydrate form of IrO 2 as the anode catalyst in alkaline media can achieve onset cell potentials as low as −1.55 V with a cathode overpotential of only 0.02 V, partial current densities for CO as high as 250 mA cm −2 (compared to ∼130 mA cm −2 with a Pt anode), and energy efficiencies as high as 70%. The IrO 2 non-hydrate proved to be much more durable by maintaining more than 90% of its activity after cycling the anode potential over the 0 to 1.0 V vs. Ag/AgCl range for over 200 times, whereas the dihydrate lost most of its activity after 19 cycles. Possible causes for these differences are discussed. This work shows that improvements to the anode, so to the OER, can drastically improve the prospects of the electrochemical reduction of CO 2 to useful chemicals.

Layered double hydroxide (LDH) materials, especially metal–organic framework (MOF)-derived LDHs, have attracted much attention in electrochemical capacitor applications. However, the construction of porous three-dimensional microsphere architectures with controlled morphology is highly demanded for high-performance supercapacitor electrodes. Thus, a simple and effective strategy is recommended to design and fabricate the well-defined layered structure of LDHs with high performance. In this study, we demonstrate the synthesis of nickel–cobalt-LDHs (NiCo-LDHs) by in-situ etching of the Ni-MOF template at different hydrolysis times. Based on the different characterization results of the sample, a formation mechanism has been proposed in terms of the proton production rate and etching process. As a result of the disparity in the layered structure and the surface area, the electrochemical behavior of the NiCo-LDHs has been altered. The sample NiCo-LDH/10 (prepared after the 10 h reaction) exhibited a high surface area and the large size of LDH sheets on microspheres, which promoted the rapid electrolyte ion transportation for supercapacitors and displayed a maximum specific capacity of 1272 C g–1 at 2 A g–1. In addition, the assembled asymmetric supercapacitor delivered a remarkable energy density of 36.1 Wh kg–1 with an outstanding cyclic stability (103.9% after 5000 cycles). This work establishes an effective strategy to synthesize a well-defined NiCo-LDH structure from the MOF template toward high-performance asymmetric supercapacitors, which could be extended to large-scale preparation of other transition metal-based LDHs from Ni-MOFs.

Electrochemical reduction of CO2 was a widespread method for CO2 conversion into valuable chemical fuel. C2H4 is an important product from CO2 reduction. However, conversion of CO2 into the hydrocarbon C2H4 faced large energy barriers. Herein, we, for the first time, achieve a high efficiency for electrochemical conversion of CO2 to C2H4 on a tin-modified CuO. By modifying with Sn, we obtained a related low onset potential of C2H4 as positive as −0.8 V versus RHE and a high Faradaic efficiency of C2H4 as high as 22% at −1.0 V (vs RHE). According to density functional calculation, the Sn dopant mainly enriched the electron density of CuO, while it was electron-poor in the Sn dopants. The rate of CO2 reduction can be enhanced on Cu nanosheets with higher electron density. We believed that this work would promote the development of two-dimensional catalysts for CO2 conversion and deepen the understanding of doping on CO2 reduction.