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Sn-based electrocatalysts are exceptionally competitive for electrochemical reduction of CO2 (CO2ER) applications. The rate-controlling step of Sn-based catalysts, extensively investigated through experiment and theoretical studies, primarily involves the electron transfer process from CO2 to form surface-adsorbed *CO2˙−. In light of this, the introduction of amines to enhance guest–host interaction for CO2 adsorption and simultaneously reduce the reaction energy barrier is an innovative tactic that will make a decisive contribution to improving the CO2ER performance. Herein, an aniline modified tin oxide composite catalyst (SnO2/PDA0.5-OCNTs) was constructed and applied to electrocatalytic CO2 reduction to produce HCOOH. A thin amorphous organic aniline layer was formed on the exterior of oxidized carbon nanotubes (OCNTs), which anchors tin oxide nanoparticles (SnO2 NPs) and improves the stability of the composite electrocatalysts. Depending on the robust chemical interactions between aniline and CO2, the captured CO2 is converted into an intriguing carbamate intermediate (NHCOO*), which reduces the reaction energy barrier through a new reaction pathway and accelerates the reaction kinetics of the rate-determining step for CO2ER to generate HCOOH. Benefiting from these merits, SnO2/PDA0.5-OCNTs delivered an excellent HCOOH faradaic efficiency (FEHCOOH) of 96% at −1.43 V (vs. RHE) with a satisfactory HCOOH partial current density (jHCOOH) of 166 mA cm−2 at −1.83 V in a flow cell. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanomaterials for electrochemical reduction of CO2 (CO2ER) to CO have been extensively investigated, evaluated, and applied recently. Nevertheless, their weak adsorption capacity for CO2 usually results in a rapidly decayed CO faradaic efficiency (FECO) in the course of pursuing a commercial CO current density (jCO) by increasing the overpotential. Herein, we axially graft pyridine molecules on nitrogen-doped carbon nanotubes to construct a metal-free composite electrocatalyst (Py-N4CNTs-800) with enhanced CO2 affinity for CO2ER to efficiently generate CO. Py-N4CNTs-800 exhibits a prominent FECO of 96% at −0.99 V (vs. reversible hydrogen electrode, RHE) with a desirable jCO of 18.4 mA cm−2, and FECO can even be maintained above 90% in a wide electrochemical potential window (−0.79 to −1.19 V). In situ infrared spectra unambiguously indicate that grafted axial pyridine molecules can facilitate the CO2 adsorption and suppress the occurrence of competitive hydrogen evolution reaction (HER). Density functional theory (DFT) calculations enlighten that the introduction of pyridine molecules could dramatically stabilize the key intermediate *COOH, which effectively accelerates the reaction kinetics rate. Notably, Py-N4CNTs-800 delivers a promising jCO of 217 mA cm−2 at −0.9 V in a flow cell, showing a bright prospect of function strengthened carbon nanomaterial for industrial applications. [ABSTRACT FROM AUTHOR]

Sn‐based electrocatalysts have shown great potential in the future industrial application of CO2 electroreduction (CO2ER) to C1 products due to their non‐toxicity and low price. However, it is a great challenge to fabricate a Sn‐based electrocatalytic system with high performance and stability. Herein, grafted pyridine was innovatively coupled with SnO2 to construct an organic‐inorganic composite (SnO2/Py‐CNTO) for highly efficient CO2ER. The detailed studies showed that pyridine and protonated pyridine coexist on the surface of SnO2/Py‐CNTO, and both play distinctive roles in promoting the selectivity of CO2ER. Benefiting from the merits, SnO2/Py‐CNTO delivered an excellent faradaic efficiency (FE) of 96 % for CO2ER at −1.29 VRHE where the HCOOH production with 85 % FE dominated, and good stability for 32 h electrolysis. The theoretical calculations showed that protonated pyridine not only facilitates the CO2 adsorption and HCOOH desorption, but also significantly reduces the limiting potential for the conversion of CO2 to HCOOH. [ABSTRACT FROM AUTHOR]

Conversion of the greenhouse gas CO2 to value‐added products is an important challenge for sustainable energy research. Here, a durably nanohybrid composed of Ag nanoparticles and polyacrylamide was constructed for the selectively electroreduction of CO2 to CO. The nanohybrid exhibited an outstanding CO faradaic efficiency of 97.2±0.2 % at −0.89 VRHE (vs. the reversible hydrogen electrode) with a desirable CO partial current density of −22.0±2.3 mA cm−2 and maintained the CO faradaic efficiency above 95 % over a wide potential range (−0.79 to −1.09 VRHE), showing excellent stability during a 48 h prolonged electrolysis. The origins of selective enhancement of CO2 reduction over the nanohybrid stemmed from the activation of CO2 via hydrogen bond and the low basicity of the amide. DFT calculations implied that the synergy of Ag nanoparticles and amide could better stabilize the key intermediate (*COOH) and effectively lower the overpotential of CO2 reduction. These results establish the synergistic effects of organic/inorganic hybrid as a complementary method for tuning selectivity in CO2‐to‐fuels catalysis. [ABSTRACT FROM AUTHOR]

A novel flexible three‐dimensional (3D) architecture of lithiated carbon nanotubes (CNTs‐Li) interlacing reduced graphene oxide (rGO) loaded with NiS2 (denoted as NiS2@rGO/CNTs‐Li) was rationally designed and implemented as interlayer with dual functions to suppress lithium polysulfides (LiPSs) shuttle and enhance redox kinetics for high‐performance Li−S batteries. In our design, the introduced rGO and CNTs‐Li serve as the conductive skeleton for facilitating the fast electron/ion transfer, while the infixing NiS2 catalyst could synchronously entrap the soluble LiPSs and speed up their interconversion. The chemical interaction between NiS2 and LiPSs and the redox kinetics were probed by density functional theory (DFT) calculations and electrochemical measurements, respectively. Benefiting from the synergistic effect of 3D conductive skeleton and polar NiS2 catalyst, the cell with the NiS2@rGO/CNTs‐Li modified separator exhibits a high initial capacity of 1515 mA h g−1 at 0.2 C and an excellent long‐term cycling stability up to 600 cycles with a low decay rate of 0.071% at 2.0 C. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs)‐supported metal‐based catalysts applied in the electrochemical reduction of CO2 (CO2ER) have attracted extensive research recently. Nevertheless, insight into the roles of surface oxygen functional groups in these catalysts on CO2ER is still deficient. Herein, three catalysts were reasonably fabricated by chemically loading Ag nanoparticles (NPs) on the oxygenic CNTs (CNT−COOH, CNT−OH and CNT−CO) with precise tuning oxygen functional groups, and then used to explore the effect of oxygen functional groups on the electrocatalytic performance of Ag NPs for CO2ER. Compared with the other two counterparts, Ag/CNT−COOH with the highest content of carboxyl groups possesses the most uniform size and dispersion of Ag NPs and the strongest surface acidic environment, which enable it to exhibit the highest current density and Faradaic efficiency for CO production at high overpotential region (E≤−1.0 V vs. RHE). This work broadens the understanding of surface oxygen functional groups of catalysts in enhancing CO2ER performance, and provides guidance for the design and synthesis of high‐performance catalysts. [ABSTRACT FROM AUTHOR]

Developing the conductive and catalytic composite interface is an efficient way to boost up the conversion of lithium polysulfide (LiPSs) that can effectively resolve the shuttle effect. Besides, achieving the high performance with low metal loading has practical significance for the commercialization of lithium–sulfur (Li−S) batteries. Herein, the chainmail catalyst of Fe3O4@C/CNTO was prepared by annealing the iron phthalocyanine (FePc)/oxidized carbon nanotubes (CNTO) precursor in which FePc was used as iron and carbon sources and CNTO was functionalized as oxygen source and catalyst support. The conductive composite catalyst with low metal loading (5.4 wt%) was applied into the coating layer of Celgard separator with duplex functions in trapping and catalyzing intercepted LiPSs for high‐performance Li−S batteries. This work can help us to understand the importance of conductive and catalytic composite interface for promotion of LiPSs conversion and also offer a more feasible synthesis method of electrocatalyst for other energy storage systems. [ABSTRACT FROM AUTHOR]

Selective electrochemical reduction of CO2 by using renewable electricity has received considerable attention because of the potential to convert a harmful greenhouse gas into useful chemicals. A high‐performance electrocatalyst for CO2 reduction is constructed based on metal nanoparticles/organic molecule hybrid materials. On the nanoscale, Au nanoparticles are uniformly anchored on carbon nanotubes to afford substantially increased current density, improved selectivity for CO, and enhanced stability. On the molecular level, the catalytic performance is further enhanced by introducing axial pyridine groups to the surface of the carbon nanotubes. The resulting hybrid catalyst exhibits around 93 % faradaic efficiency for CO production over a wide potential range (−0.58 to −0.98 V), a high mass activity of 251 A gAu−1 at −0.98 V in aqueous solution at near‐neutral pH, and strong stability with continuous electrolysis for 10 h at −0.58 V. DFT calculations indicate that the synergistic effects of Au and axial pyridine could dramatically stabilize the key intermediate (*COOH) formed in the rate‐limiting step of CO2 reduction, which effectively lowers the overpotential. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: Selectively electrochemical conversion of CO2 into organic fuel using renewable electricity is one of the most sought‐after processes. In this paper, we report the electrochemical reduction of CO2 (CO2RR) on the nanoporous Ag electrodes made of compacted Ag nanoparticles (AgNPs), which were prepared by one‐step reduction in the water phase with or without the surfactant sodium dodecyl sulfate (SDS). The scanning electron microscope (SEM) characterizations show that the compacted Ag electrodes have the nanoporous morphology formed by stacking AgNPs. Compared with the nanoporous Ag electrode without SDS modification (C‐AgNPs), the SDS‐modified AgNPs electrode (C‐AgNPs‐SDS) is highly effective in improving selective CO production in a wide range of potentials (–0.69 V — –1.19 V, vs. RHE), with a Faradaic efficiency of 92.2% and a current density of –8.23 mA·cm–2 for CO production at –0.79 V (vs. RHE). C‐AgNPs‐SDS is also catalytically stable with only less than 7% deactivation after 8 h of continuous electrolysis. Nanoporous Ag electrodes were prepared through mechanically compressing AgNPs which were synthesized by one‐step reduction in the water phase without and with the surfactant sodium dodecyl sulfate (SDS). The SDS‐modified AgNPs electrode (C‐AgNPs‐SDS) exhibits the best catalytic performance for selectively converting CO2 to CO. [ABSTRACT FROM AUTHOR]