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Despite  possessing 5-fold higher specific energy density compared to commercial lithium-ion batteries, the insulating nature of sulfur and its reductive derivatives along with the uncontrollable migration of polysulfides hinder the commercialization of lithium-sulfur technology. Herein a bilayer cathode consisting of nitrogen sulfur codoped porous carbon network and titanium carbide has been introduced and investigated methodically. The porous sulfur host promotes uninterrupted diffusion of electrolyte and ions whereas titanium carbide acts as polysulfide trapping material. The superiority of this bilayer cathode over the conventional interlayer approach has been highlighted in terms of the diffusivity of lithium ions and the overall ohmic resistance. Variation in interfacial charge transfer resistance during charging and discharging has been investigated using dynamic electrochemical impedance spectroscopy. Discharge capacity reaches as high as 1300 mA h g–1 at 0.1 C with a Coulombic efficiency of 99%. Theoretical studies reveal that the polar nature and improved interfacial charge transfer between the TiC and polysulfides result in excellent binding strength and faster redox kinetics during operation, respectively. This work provides an experimental as well as theoretical evidence of the bifunctional mechanism of TiC toward polysulfide confinement and conversion.

Development of a cost-effective and highly efficient electrocatalyst is essential but challenging in order to convert carbon dioxide to value-added chemicals at ambient conditions. In the current work, the activity of a full electrochemical cell has been demonstrated, utilizing a proton exchange membrane CO 2 conversion cell that can selectively convert carbon dioxide to a value-added chemical (formic acid) at room temperature and pressure. A cost-effective, nonprecious-metal-based electrocatalyst, nitrogen-doped carbon nanotubes encapsulating Fe 3 C nanoparticles (Fe 3 C@ NCNTs), has been reported to exhibit superior catalytic activity toward the electrochemical CO 2 reduction reaction (CO 2 RR). A facile one-step synthesis procedure has been undertaken to synthesize Fe 3 C@NCNTs. CO 2 adsorption takes place via sharing of charge between the nucleophilic anchoring site (Fe 3 C) and the electrophilic C site of CO 2 , as shown by the DFT studies. The porous architecture, unique tubular structure, high graphitization degree, and appropriate doping of the Fe 3 C-encapsulating NCNTs allow better three-phase contact of CO 2 (gas), H 2 O (liquid), and catalyst (solid), which can enhance the electrocatalytic activity of the cell, as demonstrated by the experimental findings. The cell was tested under a continuous flow of CO 2 gas and has been demonstrated to produce a good amount of formic acid (HCOOH). The production of formic acid was examined by utilizing UV−vis spectroscopy and high-performance liquid chromatography (HPLC). A series of designed experiments disclosed that the maximum yield of formic acid was as high as 90% with Fe 3 C@NCNTs as both anode and cathode catalysts. Technology to scale up the reduction procedure has also been proposed and shown in this particular work. These unique observations open a route for the development of cost-effective and highly active platinum-free electrocatalysts for the CO 2 RR.

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