Room-temperature sodium−sulfur batteries have potential in stationary applications, but challenges such as loss of active sulfur and low electrical conductivity must be solved. Nitrogen-doped nanocarbon host cathodes have been employed in metal−sulfur batteries: polar interactions mitigate the loss of sulfur, while the conductive nanostructure addresses the low conductivity. Nevertheless, these two properties run contrary to each other as greater nitrogen-doping of nanocarbon hosts is associated with lower conductivity. Herein, we investigate the polarity−conductivity dilemma to determine which of these properties have the stronger influence on cycling performance. Lower carbonization temperatures produce more pyridinic nitrogen and pyrrolic nitrogen, which from density functional theory calculations preferentially bind discharge products (Na 2 S and short-chain polysulfides). Despite its lower conductivity, the highly doped composite showed better Coulombic efficiency and stability, retaining a high capacity of 980 mAh g (S)−1 after 800 cycles. Our findings represent a paradigm shift where nitrogen-doping should be prioritized in designing shuttle-free, long-life sodium−sulfur batteries.

Intensive research in electrochemical CO2 reduction reaction has resulted in the discovery of numerous high-performance catalysts selective to multi-carbon products, with most of these catalysts still being purely transition metal based. Herein, we present high and stable multi-carbon products selectivity of up to 76.6% across a wide potential range of 1 V on histidine-functionalised Cu. In-situ Raman and density functional theory calculations revealed alternative reaction pathways that involve direct interactions between adsorbed histidine and CO2 reduction intermediates at more cathodic potentials. Strikingly, we found that the yield of multi-carbon products is closely correlated to the surface charge on the catalyst surface, quantified by a pulsed voltammetry-based technique which proved reliable even at very cathodic potentials. We ascribe the surface charge to the population density of adsorbed species on the catalyst surface, which may be exploited as a powerful tool to explain CO2 reduction activity and as a proxy for future catalyst discovery, including organic-inorganic hybrids.