Zachary J. Schiffer

Temperature strongly influences chemical reactivity, but its impact on electrochemical synthesis is still being uncovered. Here, we develop an analytical framework using first-order estimates to build intuition for the impact of temperature on electrochemical kinetics, thermodynamics, and energetics. We first identify 80−260 °C as a practical, intermediate-temperature range for industrial synthesis based on an analysis of over 2000 thermochemical patents. We then describe electrochemical kinetics in terms of two scalar values that indicate to what extent added heat reduces overpotential requirements. Literature kinetic data suggest a benefit of about 1 mV/K extending to intermediate temperatures. When thermodynamics, kinetics, and cell resistance are considered together, we find that higher operating temperatures often reduce overall energy requirements. Ultimately, by applying fundamental electrochemical equations to existing data, we show that intermediate temperatures can not only enable kinetically difficult reactions but also can reduce additional heating and cooling costs, making temperature essential for practical electrochemical synthesis.

Electrosynthesis offers a direct route to utilize clean electricity to create low‑emission pathways for chemical manufacturing. For direct electrosynthesis of highly active compounds such as hydrogen peroxide (H 2 O 2 ), however, the close coupling of product formation and decomposition at electrode interfaces, together with energy intensive product–electrolyte separation, leads to energy losses and limited scalability. Here, we develop an electrified supported liquid membrane platform as a scalable and practical method for H 2 O 2 production as an important model compound. In this architecture, electrons from an external power source are temporarily stored in a designed organic mediator that is subsequently autoxidized within a physically segregated supported liquid membrane domain. This structural-decoupling strategy suppresses electrode driven decomposition, simplifies product handling, and permits independent tuning of electrochemical, transport, and product formation environments within a compact, modular device constructed from inexpensive components. The platform produces metal-free aqueous H 2 O 2 at concentrations above 1 g L -1 with Faradaic efficiencies up to 80%. We further demonstrate direct, on‑site utilization of the generated oxidizing equivalents via in situ Fenton oxidation of an organic contaminant, thereby converting intermittent renewable electricity into localized water-treatment capability. More broadly, this strategy establishes an integrated and flexible reactor design framework for multiphase, electrochemically mediated synthetic processes beyond H 2 O 2 .

Distributed production of hydrazine, an energy-dense fuel and valuable commodity chemical, can enable energy resilience and flexibility in resource-constrained areas. In this work, we electrify the Bayer Ketazine process and demonstrate a bench-top device for modular, distributed hydrazine production. By implementing an anode assembly with gas permeable membrane, we electrochemically produce bleach with transient chlorine gas in the system, achieving a 75% Faradaic efficiency and concentrations of up to 1.67 ± 0.02 M, an order of magnitude more concentrated than conventional onepot electrochemical bleach production systems. When combined in a tandem reactor setup, we used this electrochemically generated hypochlorite to synthesize hydrazine, achieving 25% electron-to-azine efficiency while looping the hypochlorite via recycling of the sodium chloride salt. This system demonstrates that electrochemical processes can enable modular production of fuels and commodity chemicals, enabling access to these important chemicals and fuels in logistically isolated locations with limited feedstocks.

Green synthesis of hydrogen peroxide (H2O2) using renewable electricity remains a substantial challenge due to strict requirements of complex catalysts and unavoidable H2O2 decomposition in electrochemical reactors. Here we report a compact electrified phenazine autoxidation (e-PAO) platform that couples an alkaline electrolyzer and a supported liquid membrane (SLM) reactor for continuous, high-purity H2O2 production. This electrified phenazine mediation system avoids the use of precious metal catalysts and gaseous reactants in electrocatalytic and conventional thermocatalytic H 2 O2 manufacture systems. The concept of SLM is applied to integrate hydrogenation, autoxidation and extraction into a single module, efficiently shuttling electrons from the aqueous electrolyte to H2O2 product across a fixed nonaqueous medium with Faradaic efficiency up to 80%. In this SLM architecture, separating electroreduction from H2O2 formation into distinct environments mitigates the H2O2 decomposition that is widespread in other electrochemical methods. We demonstrate direct applicability to advanced oxidation via in-situ Fenton treatment of organic pollutants, highlighting the potential of the e-PAO platform for modular, on demand H2O2 generation and wastewater remediation. This strategy provides an integrated and flexible reactor-construction framework for multiphase, electrochemically mediated synthetic processes.

Electrochemistry offers a complementary pathway for chemical manufacturing, providing benefits beyond traditional thermochemical processes, but most systems are constrained to near-ambient temperatures due to solvent limitations. This leaves an underexplored intermediate-temperature regime (100–300 °C) between aqueous and solid-state electrolytes where many industrial reactions operate and heat is accessible at scale. Ionic liquids (ILs) are uniquely suited to operating in this regime. They combine robust thermal stability, wide electrochemical windows, high ionic efficiency, and tunable chemical properties. ILs have already been applied in devices such as fuel cells, water splitting, and high-temperature energy storage, but their use for electrochemical synthesis above 100 °C remains largely unexplored. Here we highlight how ILs can enable both mechanistic studies and practical electrochemical systems at elevated temperatures while outlining the challenges of cost, viscosity, compositional diversity, and device integration. Harnessing these opportunities could establish ILs as key electrolytes for bridging electrocatalysis and thermocatalysis.

Temperature strongly influences chemical reactivity, yet its impact on electrochemical synthesis is still being uncovered. Here, we build an analytical framework using first-order estimates to build intuition for the impact of temperature on electrochemical kinetics, thermodynamics, and energetics. We first identify 80 - 260 °C as a practical, intermediate-temperature range for industrial synthesis based on an analysis of over 2000 thermochemical patents. We then describe electrochemical kinetics in terms of two scalar values that indicate to what extent added heat reduces overpotential requirements. Literature kinetic data suggest a benefit of about 1 mV/K extending to intermediate temperatures. When thermodynamics, kinetics, and cell resistance are considered together, we find that higher operating temperatures often reduce overall energy requirements. Ultimately, by applying fundamental electrochemical equations to existing data, we show that intermediate temperatures can not only enable kinetically difficult reactions but also can reduce additional heating and cooling costs, making temperature essential for practical electrochemical synthesis.

High Resolution Image Download MS PowerPoint Slide Management of the electrode surface temperature is an understudied aspect of (photo)electrode reactor design for complex reactions, such as CO 2 reduction. In this work, we study the impact of local electrode heating on electrochemical reduction of CO 2 reduction. Using the ferri/ferrocyanide open circuit voltage as a reporter of the effective reaction temperature, we reveal how the interplay of surface heating and convective cooling presents an opportunity for cooptimizing mass transport and thermal assistance of electrochemical reactions, where we focus on reduction of CO 2 to carbon-coupled (C 2+ ) products. The introduction of an organic coating on the electrode surface facilitates well-behaved electrode kinetics with near-ambient bulk electrolyte temperature. This approach helps to probe the fundamentals of thermal effects in electrochemical reactions, as demonstrated through Bayesian inference of Tafel kinetic parameters from a suite of high throughput experiments, which reveal a decrease in overpotential for C 2+ products by 0.1 V on polycrystalline copper via 60 °C surface heating.

The hydrodynamics of electrochemical CO 2 reduction (CO 2 R) systems is an insufficiently investigated area of research that has broad implications on catalyst activity and selectivity. While most previous reports are limited to laminar and CO 2 -sparged systems, herein we address a wide range of hydrodynamics via electrolyte recirculation systems. We find that increased hydrodynamics at the electrode surface results directly in changes to the ethylene and methane Tafel slopes, demonstrating that mass transport is on equal footing with catalyst active sites in determining reaction mechanisms and the ensuing product distribution. Mass transport is traditionally considered to be in the purview of systems-level engineering, yet the present work shows that CO 2 R mechanistic work must be considered in the context of the mass transport conditions. We extend our analysis to organic coatings, demonstrating that the films shield the active sites from variability in hydrodynamics and increase the residence time of CO so that it may be further reduced to desirable products.

Management of the electrode surface temperature is an understudied aspect of (photo)electrode reactor design in both fundamental studies and optimized systems for complex reactions such as CO2 reduction. In this work, we study the impact of local electrode heating on electrochemical CO2 reduction. Using the ferri/ferrocyanide open circuit voltage as a reporter of the effective reaction temperature, we reveal how the interplay of surface heating and convective cooling poses a challenge for co-optimizing mass transport and thermal assistance of electrochemical reactions, where we focus on reduction of CO2 to carbon-coupled (C2+) products. The introduction of an organic coating on the electrode surface facilitates well-behaved electrokinetics with near-ambient bulk electrolyte temperature, enabling the discovery that surface heating to 60 °C decreases the voltage required for peak C2+ performance by ca. 100 mV compared to ambient conditions. This approach to thermal management offers a new dimension to electrochemical systems design. It moreover offers the opportunity to further probe thermal effects in electrochemical reactions, as demonstrated through Bayesian inference of Butler-Volmer kinetic parameters from a suite of high throughput experiments.

High Resolution Image Download MS PowerPoint Slide The hydrodynamics of electrochemical CO 2 reduction (CO 2 R) systems is an insufficiently investigated area of research that has broad implications on catalyst activity and selectivity. While most previous reports are limited to laminar and CO 2 -sparged systems, herein we address a wide range of hydrodynamics via electrolyte recirculation systems. We find that increased hydrodynamics at the electrode surface results directly in changes to the ethylene and methane Tafel slopes, demonstrating that mass transport is on equal footing with catalyst active sites in determining reaction mechanisms and the ensuing product distribution. Mass transport is traditionally considered to be in the purview of systems-level engineering, yet the present work shows that CO 2 R mechanistic work must be considered in the context of the mass transport conditions. We extend our analysis to organic coatings, demonstrating that the films shield the active sites from variability in hydrodynamics and increase the residence time of CO so that it may be further reduced to desirable products.

The hydrodynamics of electrochemical CO2 reduction (CO2R) systems is an insufficiently investigated area of research that has broad implications on catalyst activity and selectivity. While most previous reports are limited to laminar and CO2-sparged systems, herein we address a wide range of hydrodynamics via electrolyte recirculation systems. We find that increased hydrodynamics at the electrode surface results directly in changes to the ethylene and methane Tafel slopes, demonstrating that mass transport is on equal footing with catalyst active sites in determining reaction mechanisms and the ensuing product distribution. Mass transport is traditionally considered to be in the purview of systems-level engineering, yet the present work shows that CO2R mechanistic work must be considered in the context of the mass transport conditions. We extend our analysis to organic coatings, demonstrating that the films shield the active sites from variability in hydrodynamics and increase the residence time of CO so that it may be further reduced to desirable products.

One key strategy toward decarbonizing chemical synthesis is to reduce reliance on fossil fuels as an energy source. The increased availability of renewable electricity from sources such as solar and wind offers opportunities to both reduce reliance on fossil fuels and electrify chemical manufacturing. While there are many possible uses for renewable electricity, such as joule heating of reactors, one approach is to use these electrons to make and break chemical bonds directly via electrochemistry.