The activity for an electrocatalyst for the oxygen reduction reaction (ORR) is most often assessed using bare metal electrodes in direct contact with an aqueous electrolyte. This architecture allows all reactants and products to have equivalent geometric access to the catalyst surface, but this does not always lead to an optimal reaction environment. By adding an intermediate phase as a layer between the catalyst and the electrolyte, diffusive driving forces can be engineered into the system to force reactants to the catalyst and products away from it, increasing the overall system activity. For instance, previous research explored nanoporous Ni/Pt electrodes encapsulated with the ionic liquid [MTBD][beti]. The high oxygen solubility in this ionic liquid was thought to explain the nearly doubled increase in the composite electrocatalyst activity, but it is possible that other ionic liquid properties (water solubility, oxygen diffusivity, ionic conductivity, viscosity) might also be affecting ORR activity. In this work, we surveyed a number of ionic liquids in nanoporous NiPt/ionic liquid composite catalysts with an eye toward clarifying to what extent the physical properties of the IL have on the activity of the composite ORR catalyst. Overall, we find the oxygen solubility and water solubility most strongly affect the decrease in ORR overpotential. The cathodic oxygen reduction reaction (ORR) is the most inefficient component of hydrogen fuel cells, and implementation of this technology will require better catalysts for this reaction. The 4-electron ORR has been studied for many decades. It is a complex catalytic reactioninvolving mass transport of oxygen molecules and protons to a catalytic metal surface, and (in the absence of an aqueous solution) expulsion of product water away from this surface. Both theoretical and experimental work has led to many improvements in Ptbased catalysts for the ORR, from geometric alterations of the catalyst increasing the active surface area through nanoparticle shape control, 1 to porosity formation, 2 to alloying Pt with transition metals. 3While these adjustments have improved activity over commercially available catalysts, it remains unclear that these increases are sufficient for the adoption of fuel cells into mainstream automotive applications. 4 Previously explored in our group is a composite catalyst for oxygen reduction using a dealloyed nanoporous nickel-platinum catalyst (npNiPt) impregnated with an ionic liquid (IL) whose properties bias the reaction kinetics for the ORR to completion. This approach increases the aggregate catalytic activity of the composite by a multiplicative factor of the base np-NiPt catalyst activity.5 This strategy was recently used by Stamenkovic, et al. to make a composite Ni/Pt nanoframe + IL catalyst that has resulted in a 36-fold increase in activity for the ORR compared to neat Pt. 6 However, fundamental electrochemical principles and measurements have not been made for the porous catalyst + IL composite, and it is the purpose of this ...

A methodology for calibrating pH meters in highly alkaline solutions such as those relevant to cementitious systems is presented. This methodology uses an extended form of the Debye-Hückel equation to generate a calibration curve of pH vs. the measured electrochemical potential (mV) based on a series of aqueous alkali hydroxide solutions of known concentrations. This methodology is compared with the 'built-in' process of calibration based upon pH 4, 7, and 10 standard solutions. The built-in calibration process underestimates the real pH values by up to 0.3 log units, which is attributed to the alkali error. A spreadsheet for

While the incineration of biomass residues is gaining traction as a globally available source of renewable energy, the resulting ash is often landfilled, resulting in the disposal of what could otherwise be used in value-added products. This research focuses on the beneficial use of predominantly rice husk and sugarcane bagasse-based mixed biomass ashes, obtained from two paper mills in northern India. A cementitious binder was formulated from biomass ash, clay, and hydrated lime (70:20:10 by mass, respectively) using 2M NaOH solution at a liquid-to-solid mass ratio of 0.40. Compressive strength of the biomass ash binder increased linearly with compaction pressure, indicating the role of packing density. Between the two mixed biomass ashes used in this study, the one with higher amorphous content resulted in a binder with higher strength and denser reaction product. Multi-faceted characterization of the biomass ash binder indicated the presence of aluminum-substituted calcium silicate hydrate, mainly derived from the pozzolanic reaction.

An untapped source of amorphous SiO2, industrially generated Indian biomass ash (SA)—90% amorphous, with composition of ~60% SiO2 and ~20% unburnt carbon—can be used to produce cementitious and alkali‐activated binders. This study reports dissolution of amorphous Si from SA in 0.5 mol/L and 1 mol/L aqueous NaOH, with and without added Ca(OH)2, at SA:Ca(OH)2 wt% ratios of 100:0, 87.5:12.5, and 82.5:17.5. Monitoring of elemental dissolution and subsequent/simultaneous product uptake by ICP‐OES offers an effective process for evaluating utility of industrial wastes in binder‐based systems. After 28 days in solution, up to 68% of total Si is dissolved from SA in 1 mol/L NaOH, with values as much as 38% lower in the presence of Ca(OH)2, due to the formation of tobermorite‐like C‐S‐H. FTIR, 29Si MAS‐NMR, and XRD are used to characterize solid reaction products and observe reaction progress. Product chemistries calculated from ICP‐OES results and verified by selective dissolution in EDTA/NaOH—namely, Ca/Si of 0.6‐1 and Na adsorption of 1‐2 mmol/g—are found to be consistent with those indicated by aforementioned techniques. This indicates the efficacy of ICP‐OES in estimating product chemistry via such a methodology.

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