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Three-dimensional host structures with superior sodiophilicity and low nucleation barriers can help combat the complex failure modes of Na metal anodes originating from accelerated dendrite formation, anodic corrosion, and electrolyte depletion. This work reports the fabrication of a unique super-sodiophilic, defect-rich and hierarchically porous skeletal carbon nanofiber (SCNF) host for SCNF@Na anodes using electrospinning of the low-cost, renewable lignin biopolymer. The uniform nucleation and plating of Na effectuated by the hierarchically porous structure coupled with the defect-induced formation of a resilient, F-rich solid electrolyte interface (SEI) layer offers excellent protection to the metallic anode. The defect-rich porous structure plays an important role in mediating dense Na nucleation, planar growth, and electrochemical stability according to the depth profiling experiments and density functional theory calculations. The SCNF@Na composite anode maintains high Coulombic efficiencies (CEs) and electrochemical reversibility in asymmetric and symmetric cells. The full cells prepared by interfacing the SCNF@Na anode with a Na3V2(PO4)2F3 cathode delivers exceptional capacity retention of 106 mAh g–1 for 350 cycles with an average CE of 99.2% at 1C, and 103 mAh g–1 after 200 cycles at 4C. Such rationally designed carbon hosts derived from biopolymers open a new avenue for safe and low-cost metal batteries. © 2022 Wiley-VCH GmbH

Recommender Systems (RS) are widely used to help people or group of people in finding their required information amid the issue of ever-growing information overload. The existing group recommender approaches consider users to be part of a single group only, but in real life a user may be associated with multiple groups having conflicting preferences. For instance, a person may have different preferences in watching movies with friends than with family. In this paper, we address this problem by proposing a Hybrid Two-phase Group Recommender Framework (HTGF) that takes into consideration the possibility of users having simultaneous membership of multiple groups. Unlike the existing group recommender systems that use traditional methods like K-Means, Pearson correlation, and cosine similarity to form groups, we use Fuzzy C-means clustering which assigns a degree of membership to each user for each group, and then Pearson similarity is used to form groups. We demonstrate the usefulness of our proposed framework using a movies data set. The experiments were conducted on MovieLens 1M dataset where we used Neural Collaborative Filtering to recommend Top-k movies to each group. The results demonstrate that our proposed framework outperforms the traditional approaches when compared in terms of group satisfaction parameters, as well as the conventional metrics of precision, recall, and F-measure.

Environmental and energy considerations demand that the Haber-Bosch process for reducing N-2 to NH3 be replaced with electrochemical ammonia synthesis where the H atoms come from water instead of from H-2. But a practical realization of electrochemical N-2 reduction reaction (NRR) requires the development of new generation electrocatalysts with low overpotential and high Faraday efficiency (FE). A major problem here is that the hydrogen evolution reaction (HER) competes with NRR. Herein, we consider new generation dual-site catalysts involving two different metals incorporated into a novel two-dimensional C3N-C2N heterostructure that provides a high concentration of well-defined but isolated active sites that bind two distinct metal atoms in a framework that facilitates electron transfer. We report here the mechanism and predicted kinetics as a function of applied potential for both NRR and HER for the (Fe-Ru)/C3N-C2N dual atom catalyst. These calculations employ the grand canonical potential kinetics (GCP-K) methodology to predict reaction free energies and reaction barriers as a function of applied potential. The rates are then used in a microkinetic model to predict the turn-over-frequencies (TOF) as a function of applied potential. At U = 0 V, the FE for NRR is 93%, but the current is only 2.0 mA cm(-2). The onset potential (at 10 mA cm(-2)) for ammonia on Fe-Ru/C3N-C2N is -0.22 V-RHE. This leads to a calculated TOF of 434 h(-1) per Fe-Ru site. We expect that the mechanisms for NRR and HER developed here will help lead to new generations of NRR with high TOF and FE.