Hybrid Acid/Base Electrolytic Cell for Hydrogen Generation and Methanol Conversion Implemented by Bifunctional Ni/MoN Nanorod Electrocatalyst.

Combining the methanol oxidation reaction (MOR) and hydrogen evolution reaction (HER) within an integrated electrolytic system may offer the advantages of enhanced kinetics of the anode, reduced energy consumption, and the production of high-purity hydrogen. Herein, it is reported the construction of Ni─MoN nanorod arrays supported on a nickel foam substrate (Ni─MoN/NF) as a bifunctional electrocatalyst for electrocatalytic hydrogen production and selective methanol oxidation to formate. Remarkably, The optimal Ni─MoN/NF catalyst displays exceptional HER performance with an overpotential of only 49 mV to attain 10 mA cm-2 in acid, and exhibits a high activity for MOR to achieve 100 mA cm-2 at 1.48 V in alkali. A hybrid acid/base electrolytic cell with Ni─MoN/NF electrode as anode and cathode is further developed for an integrated HER-MOR cell, which only requires a voltage of 0.56 V at 10 mA cm-2 , significantly lower than that of the HER-OER system (0.70 V). The density functional theory studies reveal that the incorporation of Ni effectively modulates the electronic structure of MoN, thereby resulting in enhanced catalytic activity. The unique combination of high electrocatalytic activity and excellent stability make the Ni─MoN/NF catalyst a promising candidate for practical applications in electrocatalytic hydrogen production and methanol oxidation.

"Why Not Stoichiometry" versus "Stoichiometry­Why Not?" Part III: Extension of GATES/GEB on Complex Dynamic Redox Systems.

In the third part of a series of articles issued under a common title, some examples of complex dynamic redox systems are presented and considered from analytical and physico-chemical viewpoints; the analysis is a leitmotiv for detailed, physico-chemical considerations. All attainable physico-chemical knowledge is involved in algorithms applied for resolution of the systems, realized with use of iterative computer programs. The first redox system (System I) is related to titration of FeSO4 + H2C2O4 with KMnO4 solution in acidic (H2SO4) medium, where simultaneous determination of both analytes from a single curve of potentiometric titration is possible. The possibility of the formation of precipitates (FeC2O4 and/or MnC2O4) in this system is taken into considerations. The second system (System II) relates to the complete analytical procedure involved in the iodometric determination of Cu; four consecutive steps of this analysis are considered. As a reasonable tool for explanation of processes occurring during simulated redox titration, speciation diagrams are suggested. This explanation is based on graphical presentation of results obtained from the calculations. The calculations made for this purpose are performed in accordance with principles of the generalized approach to electrolytic systems (GATES) with generalized electron balance (GEB) or GATES/GEB and realized with use of iterative computer programs offered by MATLAB. The reactions proceeding in this system can be formulated, together with their efficiencies, at any stage of the titration. Stoichiometry is considered as the derivative concept when put in context with GATES/GEB. The article illustrates the enormous possibilities and advantages offered by GATES/GEB.

"Why not stoichiometry" versus "stoichiometry--why not?" Part I: General context.

The elementary concepts involved with stoichiometry are considered from different viewpoints. Some examples of approximate calculations made according to the stoichiometric scheme are indicated, and correct resolution of the problems involved is presented. The principles of balancing chemical equations, based on their apparent similarities with algebraic equations, are criticized. The review concerns some peculiarities inherent in chemical reaction notation and its use (and abuse) in stoichiometric calculations that provide inconsistent results for various reasons. This "conventional" approach to stoichiometry is put in context with the generalized approach to electrolytic systems (GATES) established by Michalowski. The article contains a number of proposals that could potentially be taken into account and included in the next edition of the Orange Book. Notation of ions used in this article is not, deliberately, in accordance with actual IUPAC requirements in this respect. This article is intended to be provocative with the hope that some critical debate around the important topics treated should be generated and creatively expanded in the scientific community.