Continued advancements in the electrochemical reduction of CO 2 (CO 2RR) have emphasized that reactivity,selectivity, and stability are not explicit material properties butcombined effects of the catalyst, double-layer, reaction environ- ment, and system configuration. These realizations have steadily built upon the foundational work performed for a broad array of transition metals performed at 5 mA cm−2, which historically guided the research field. To encompass the changing advancements and mindset within the research field, an updated baseline at elevated current densities could then be of value. Here we seek to re-characterize the activity, selectivity, and stability of the five most utilized transition metal catalysts for CO2 RR (Ag, Au, Pd, Sn, and Cu) at elevated reaction rates through electrochemical operation, physical characterization, and varied operating parameters to provide a renewed resource and point of comparison. As a basis, we have employed a common cell architecture, highly controlled catalyst layer morphologies and thicknesses, and fixed current densities. Through a dataset of 88 separate experiments, we provide comparisons between CO-producing catalysts (Ag, Au, and Pd), highlighting CO-limiting current densities on Au and Pd at 72 and 50 mA cm−2, respectively. We further show the instability of Sn in highly alkaline environments, and the convergence of product selectivity at elevated current densities for a Cu catalyst in neutral andalkaline media. Lastly, we reflect upon the use and limits of reaction rates as a baseline metric by comparing catalytic selectivity at 10 versus 200 mA cm−2. We hope the collective work provides a resource for researchers setting up CO 2RR experiments for the first time.@en

In this work, different lanthanides (Tm3+, Er3+; Yb3+, Ho3+, Nd3+) were doped into NaYF4 via a high-temperature coprecipitation method, and followed by SiO2 coating to improve the water dispersibility, resulting in NaYF4:Tm3+, Er3+@NaYF4@SiO2 and NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 nanoparticles (NPs). The two NPs both exhibited the temperature-dependent second near-infrared (NIR-II) downshifting luminescence over the physiological range. The luminescence ratio of Tm3+ emission at 1460 nm to Er3+ emission at 1525 nm (Tm3+:3H4 → 3F4; Er3+:4I13/2 → 4I13/2) varies with temperature increase, as well as Yb3+ emission at 980 nm and Ho3+ emission at 1150 nm (Yb3+:2F5/2 → 2F7/2; Ho3+:5I6 → 5I8). The highest relative sensitivity of NaYF4:Tm3+, Er3+@NaYF4@SiO2 and NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 aqueous suspension is 0.36% K−1 (at 298 K) and 0.76% K−1 (at 343 K), respectively. The biological tests prove the good biocompatibility and low toxicity of the water-soluble NPs. In vitro tissue penetration experiments verify a much better penetration ability of the synthesized NaYF4:Tm3+, Er3+@NaYF4@SiO2 compared with NaYF4:Yb3+, Ho3+@NaYF4:Nd3+@SiO2 NPs. The excellent physiological luminescent thermometry with favor wave penetration depth provides a promising platform in deep tissue temperature measurement, which is very important in vivo biosensing.@en

The urgent threat of global warming and the demand for sustainable fuels have made the electroreduction of CO2 a priority, due to its possibility in closed-loop cycle of carbon. The energy conversion and strategy can diminish the content of CO2 in the atmosphere, convert renewable electricity into chemical energy and store it in chemical bonds, and gain high-value fuels or chemicals formed from CO2 conversion. However, there is much room for the improvement of the efficiency of electrocatalytic reduction of CO2. The inertness of CO2 determines a large negative potential needed for sufficient electron and proton transfer. Hence, this thesis focuses on research how the catalysts and operating conditions electrochemical influence the electrochemical CO2 reduction...@en

In this work, the highly selective and stable electrocatalytic reduction of CO2 to CO on nanostructured Ag electrocatalysts is presented. The Ag electrocatalysts are synthesized by the electroreduction of Ag2CO3 formed by in situ anodic-etching of Ag foil in a KHCO3 electrolyte. After 3 min of this etching treatment, the Ag2CO3-derived nanostructured Ag electrocatalysts are capable of producing CO with up to 92% Faradaic efficiency at an overpotential as low as 290 mV, which surpasses all of the reported Ag catalysts at identical conditions to date. In addition, the anodic-etched Ag retained ∼90% catalytic selectivity in the electroreduction of CO2 to CO for more than 100 h. The Ag2CO3-derived Ag is able to facilitate the activation of CO2 via reduction of the activation energy barrier of the initial electron transfer and provide an increased number of active sites, resulting in the dramatically improved catalytic activity for the reduction of CO2 to CO.@en

Au-Cu bimetallic thin films with controlled composition were fabricated by magnetron sputtering co-deposition, and their performance for the electrocatalytic reduction of CO 2 was investigated. The uniform planar morphology served as a platform to evaluate the electronic effect isolated from morphological effects while minimizing geometric contributions. The catalytic selectivity and activity of Au-Cu alloys was found to be correlated with the variation of electronic structure that was varied with tunable composition. Notably, the d-band center gradually shifted away from the Fermi level with increasing Au atomic ratio, leading to a weakened binding energy ofCO, which is consistent with low CO coverage observed in CO stripping experiments. The decrease in theCO binding strength results in the enhanced catalytic activity for CO formation with the increase in Au content. In addition, it was observed that copper oxide/hydroxide species are less stable on Au-Cu surfaces compared to those on the pure Cu surface, where the surface oxophilicity could be critical to tuning the binding strength ofOCHO. These results imply that the altered electronic structure could explain the decreased formation of HCOO - on the Au-Cu alloys. In general, the formation of CO and HCOO - as main CO 2 reduction products on planar Au-Cu alloys followed the shift of the d-band center, which indicates that the electronic effect is the major governing factor for the electrocatalytic activity of CO 2 reduction on Au-Cu bimetallic thin films. @en