An electrochemical cell with molten hydroxide and a Pd membrane actively extracts H2 and thereby boosts ammonia and methylcyclohexane conversion, while also delivering purified H2 ready for use.

Electrochemical polarization is now known to play a key role in thermochemical catalysis at solid–liquid interfaces. However, existing frameworks cannot account for why even nonpolar, nonfaradaic reac...

Electrochemical polarization is now known to play a key role in thermochemical catalysis at solid–liquid interfaces. However, existing frameworks cannot account for why even nonpolar, nonfaradaic reac...

Several thermochemical redox reactions have been shown to operate via the coupling of electrochemical half-reactions. Here, scanning electrochemical cell microscopy is employed to image the variations...

Several thermochemical redox reactions have been shown to operate via the coupling of electrochemical half-reactions. Here, scanning electrochemical cell microscopy is employed to image the variations...

Molecularly modified electrodes (MMEs) are potent electrocatalysts, but few principles exist for their rational design. Electrocatalysis by soluble molecules depends strongly on substituents that tune the catalyst redox potential (E1/2), but it is unclear if this parameter similarly impacts MME catalysis. Herein, we employ the hydrogen evolution reaction (HER) as a test case for comparing carbon-adsorbed cobalt phthalocyanine (CoPc/C) and cobalt hexadecafluoro-phthalocyanine (CoFPc/C). By correlating HER activity and voltammetric data to total Co surface concentration across a wide range of catalyst loadings, we find that only 5–25% of adsorbed Co sites contribute to the Co(II/I) redox wave and that this subpopulation poorly correlates with catalytic activity. Instead, in the low-loading limit, catalytic activity correlates linearly with the majority Co(II/I)-silent Co population, revealing per-site turnover frequency (TOF) values for HER. Despite a 230 mV difference in Co(II/I) redox potentials, CoPc/C and CoFPc/C display TOF values differing by less than a factor of 3 when compared over a wide potential range. Mechanistic studies point to an inner-sphere concerted proton–electron transfer step as rate-determining, suggesting that the Co–H bond dissociation free energy (BDFE) rather than the Co(II/I) E1/2 is thermodynamically relevant. Computational studies indicate that the fluoro-substituents lead to compensatory changes in Co(II/I) E1/2 and Co(I) basicity, leaving the Co–H BDFE largely unchanged between CoPc and CoFPc and thereby manifesting in similar catalytic rates. These results highlight the limited effect of E1/2-tuning on MME catalytic activity and motivate the development of methods to directly alter active site–substrate BDFE.

Surendranath Group | 318 followers on LinkedIn. An electrochemistry lab @MIT Chemistry | Global challenges in the areas of chemical catalysis, energy storage and utilization, and environmental steward...

The rate of interfacial proton-coupled electron transfer (I-PCET) to a graphite-conjugated carboxylic acid electrode depends on the concentration of nominally innocent supporting NaClO4 electrolyte. T...

The rate of interfacial proton-coupled electron transfer (I-PCET) to a graphite-conjugated carboxylic acid electrode depends on the concentration of nominally innocent supporting NaClO4 electrolyte. T...

Heterolytic hydrogenations are a key reaction class that includes CO2 reduction to formate and NADH regeneration, yet the mechanism remains unclear. Now it has been shown that this class of thermochemical reactions proceeds through an electrochemical mechanism, with polarization-driven, interfacial hydride transfer as the rate-determining step.

Heterolytic hydrogenations are a key reaction class that includes CO2 reduction to formate and NADH regeneration, yet the mechanism remains unclear. Now it has been shown that this class of thermochemical reactions proceeds through an electrochemical mechanism, with polarization-driven, interfacial hydride transfer as the rate-determining step.

Hydride transfer is an essential elementary reaction across the chemical value chain, but there are limited methods available for quantifying thermodynamic hydricity (ΔGH–), particularly among main gr...

Hydride transfer is an essential elementary reaction across the chemical value chain, but there are limited methods available for quantifying thermodynamic hydricity (ΔGH–), particularly among main gr...

Upending a long-held supposition, MIT researchers discovered that a common catalyst works by cycling between two different forms. The finding could lead to improved catalysts for industrial reactions.

ALT: a little girl is asking why not both while standing in a kitchen .

Homogeneous and heterogeneous catalysis work concurrently in a chemical process

Presently, mechanistic paradigms in catalysis generally posit that the active species remains either homogeneous or heterogeneous throughout the reaction. In this work, we show that a prominent indust...

Presently, mechanistic paradigms in catalysis generally posit that the active species remains either homogeneous or heterogeneous throughout the reaction. In this work, we show that a prominent indust...

Interfacial polarization influences catalytic reactions occurring at solid–liquid interfaces, but its measurement was previously limited to conductive materials. Now redox-active molecules enable elec...

Interfacial polarization influences catalytic reactions occurring at solid–liquid interfaces, but its measurement was previously limited to conductive materials. Now redox-active molecules enable elec...

Forward-biased bipolar membranes (FB-BPMs), which recover potential from pH gradients through ion–ion recombination, show promise for application in sustainable devices. The authors use physics-based ...