Electrolysis of metal oxides in MgCl2 based molten salts with an inert graphite anode

Eletrolysis of solid metal oxides has been demonstrated in MgCl2-NaCl-KCl melt at 700 oC taking the electrolysis of Ta2O5 as an example. Both the cathodic and anodic processes have been investigated using cyclic voltammetry, potentiostatic and constant voltage electrolysis, with the cathodic products analysed by XRD, SEM and the anodic products by GC. Fast electrolysis of Ta2O5 against a graphite anode has been realized at a cell voltage of 2 V , or a total overpotential of about 400 mV. The energy consumption was about 1 kWh/kg-Ta with a nearly 100% Ta recovery. The cathodic product was nanometer Ta powder with sizes of about 50 nm. The main anodic product was Cl2 gas, together with about 1 mol% O2 gas and trace of CO. The graphite anode was found to be an excellent inert anode. These results promise an environment-friendly and energy efficient method for metal extraction by electrolysis of metal oxides in MgCl2 based molten salts

Correction: Indirect electrosynthesis of ammonia from nitrogen and water by a magnesium chloride cycle at atmospheric pressure

(Cell Reports Physical Science 2, 100425-1–100425-15; May 19, 2021) In the originally published version of this article, Table 1 had duplicated reactions but was meant to demonstrate three different reactions: Mg3N2(s) + 6HCl(a), Mg3N2(s) + 6HCl(g), and Mg3N2(s) + 6NH4Cl(s). The corrected table appears here and now with the article online. The authors regret this error. [Table presented

More sustainable electricity generation in hot and dry fuel cells with a novel hybrid membrane of Nafion/nano-silica/hydroxyl ionic liquid

A new hybrid proton exchange membrane (PEM) has been prepared from hydroxyl functionalized imidazolium ionic liquid (IL-OH), Nafion and nano-SiO2. The IL-OH, with a hydroxyl group that acts as both a proton acceptor and donor, forms strong hydrogen bonds with both Nafion and nano-SiO2, resulting in an effective hydrogen bond network in the ternary membrane. Such an anhydrous hydrogen-bond network, which is unknown previously, endows the PEMs with higher proton conductivity, greater thermal stability and surprisingly a more robust mechanical performance than PEMs consisting of conventional ionic liquids. The resulting PEMs have a tensile strength that is more than twice as strong as recast Nafion and an anhydrous ionic conductivity of ∼55 mS cm−1 at temperatures above 160 °C, with a proton transfer number of ∼0.9. A laboratory assembled H2–O2 fuel cell employing this new PEM delivered a power density of 340 and 420 mW cm−2 at 160 and 180 °C, respectively

A Novel Discrete Group Teaching Optimization Algorithm for TSP Path Planning with Unmanned Surface Vehicles

A growing number of researchers are interested in deploying unmanned surface vehicles (USVs) in support of ocean environmental monitoring. To accomplish these missions efficiently, multiple-waypoint path planning strategies for survey USVs are still a key challenge. The multiple-waypoint path planning problem, mathematically equivalent to the traveling salesman problem (TSP), is addressed in this paper using a discrete group teaching optimization algorithm (DGTOA). Generally, the algorithm consists of three phases. In the initialization phase, the DGTOA generates the initial sequence for students through greedy initialization. In the crossover phase, a new greedy crossover algorithm is introduced to increase diversity. In the mutation phase, to balance the exploration and exploitation, this paper proposes a dynamic adaptive neighborhood radius based on triangular probability selection to apply in the shift mutation algorithm, the inversion mutation algorithm, and the 3-opt mutation algorithm. To verify the performance of the DGTOA, fifteen benchmark cases from TSPLIB are implemented to compare the DGTOA with the discrete tree seed algorithm, discrete Jaya algorithm, artificial bee colony optimization, particle swarm optimization-ant colony optimization, and discrete shuffled frog-leaping algorithm. The results demonstrate that the DGTOA is a robust and competitive algorithm, especially for large-scale TSP problems. Meanwhile, the USV simulation results indicate that the DGTOA performs well in terms of exploration and exploitation

Nanoporous Ag-Sn derived from codeposited AgCl-SnO2 for the electrocatalytic reduction of CO2 with high formate selectivity

Nanoporous Ag-Sn was prepared by direct electroreduction of a codeposited AgCl-SnO2 mixture in 0.1 M HCl, and evaluated as an electrode catalyst for the reduction of CO2 in 0.5 M KHCO3. A volcano-type correlation between selectivity for the formate product and the atomic ratio of Ag to Sn in the nanoporous catalysts was revealed. It was found that the bimetallic catalyst with a Ag:Sn ratio of 3:2, mainly composed of the Ag4Sn alloy, showed excellent catalytic performance for the conversion of CO2 to formate. This catalyst delivered a current of about 10 mA cm−2 with a high formate faradaic efficiency of about 85% at −0.8 V vs. the reversible hydrogen electrode. Moreover, the catalytic activity remained reasonably stable during a 13.5-hour electrolysis. Keywords: Ag-Sn bimetals, Solid electroreduction, Electrocatalysis, Carbon dioxide, Format