Reactive carbon capture using electrochemical reactors.

The electrolytic upgrading of CO presents a promising strategy to mitigate global CO emissions while generating valuable carbon-based products such as carbon monoxide, formate, and ethylene. However, the adoption of industrial-scale CO electrolyzers is hindered by the high energy and capital costs associated with the purification and pressurization of captured CO prior to electrolysis. One promising solution is "reactive carbon capture," which involves the electrolytic conversion of the eluent from CO capture units, or the "reactive carbon solution," directly into valuable products.

Reactive Carbon Capture Enables CO Electrolysis with Liquid Feedstocks.

ConspectusThe electrochemical reduction of carbon dioxide (CO2RR) is a promising strategy for mitigating global CO emissions while simultaneously yielding valuable chemicals and fuels, such as CO, HCOO, and CH. This approach becomes especially appealing when integrated with surplus renewable electricity, as the ensuing production of fuels could facilitate the closure of the carbon cycle. Despite these advantages, the realization of industrial-scale electrolyzers fed with CO will be challenged by the substantial energy inputs required to isolate, pressurize, and purify CO prior to electrolysis.

Visualization of CO electrolysis using optical coherence tomography.

Electrolysers offer an appealing technology for conversion of CO into high-value chemicals. However, there are few tools available to track the reactions that occur within electrolysers. Here we report an electrolysis optical coherence tomography platform to visualize the chemical reactions occurring in a CO electrolyser.

Oxygen-Resistant CO Reduction Enabled by Electrolysis of Liquid Feedstocks.

Electrolytic CO reduction fails in the presence of O. This failure occurs because the reduction of O is thermodynamically favored over the reduction of CO. Consequently, O must be removed from the CO feed prior to entering an electrolyzer, which is expensive.

Bioelectrocatalysis with a palladium membrane reactor.

Enzyme catalysis is used to generate approximately 50,000 tons of value-added chemical products per year. Nearly a quarter of this production requires a stoichiometric cofactor such as NAD/NADH. Given that NADH is expensive, it would be beneficial to regenerate it in a way that does not interfere with the enzymatic reaction.

Hydrogen Production and Utilization in a Membrane Reactor.

Industrial hydrogenation consumes ~11 Mt of fossil-derived H2 gas yearly. Our group invented a membrane reactor to bypass the need to use H2 gas for hydrogenation chemistry. The membrane reactor sources hydrogen from water and drives reactions using renewable electricity.

Catalyst Aggregation Matters for Immobilized Molecular CORR Electrocatalysts.

Here, we detail how the catalytic behavior of immobilized molecular electrocatalysts for the CO reduction reaction (CORR) can be impacted by catalyst aggregation. Raman spectroscopy was used to study the CORR mediated by a layer of cobalt phthalocyanine (CoPc) immobilized on the cathode of an electrochemical flow reactor. We demonstrate that during electrolysis, the oxidation state of CoPc in the catalyst layer is dependent upon the degree of catalyst aggregation.

High-Efficiency Perovskite Solar Cells with Sputtered Metal Contacts.

Sputter deposition produces dense, uniform, adhesive, and scalable metal contacts for perovskite solar cells (PSCs). However, sputter deposition damages the other layers of the PSC. We here report that the damage caused by sputtering metal contacts can be reversed by aerial oxidation.

Direct HO Synthesis, without H Gas.

We report here the direct hydrogenation of O gas to form hydrogen peroxide (HO) using a membrane reactor without H gas. Hydrogen is sourced from water, and the reactor is driven by electricity. Hydrogenation chemistry is achieved using a hydrogen-permeable Pd foil that separates an electrolysis chamber that generates reactive H atoms, from a hydrogenation chamber where H atoms react with O to form HO.

Conversion of Reactive Carbon Solutions into CO at Low Voltage and High Carbon Efficiency.

Electrolyzers are now capable of reducing carbon dioxide (CO) into products at high reaction rates but are often characterized by low energy efficiencies and low CO utilization efficiencies. We report here an electrolyzer that reduces 3.0 M KHCO(aq) into CO(g) at a high rate (partial current density for CO of 220 mA cm) and a CO utilization efficiency of 40%, at a voltage of merely 2.

Ring walking as a regioselectivity control element in Pd-catalyzed C-N cross-coupling.

Ring walking is an important mechanistic phenomenon leveraged in many catalytic C-C bond forming reactions. However, ring walking has been scarcely studied under Buchwald-Hartwig amination conditions despite the importance of such transformations. An in-depth mechanistic study of the Buchwald-Hartwig amination is presented focussing on ligand effects on ring walking behavior.

Electrolytic conversion of carbon capture solutions containing carbonic anhydrase.

The electrolysis of carbon capture solutions bypasses energy-intensive CO recovery steps that are often required to convert CO into value-added products. We report herein an electrochemical flow reactor that converts carbon capture solutions containing carbonic anhydrase enzymes into carbon-based products. Carbonic anhydrase enzymes benefit CO capture by increasing the rate of reaction between CO and weakly alkaline solutions by 20-fold.

Quantification of the Effect of an External Magnetic Field on Water Oxidation with Cobalt Oxide Anodes.

Here, we quantify the effect of an external magnetic field (β) on the oxygen evolution reaction (OER) for a cobalt oxide|fluorine-doped tin oxide coated glass (CoO|FTO) anode. A bespoke apparatus enables us to precisely determine the relationship between magnetic flux density (β) and OER activity at the surface of a CoO|FTO anode. The apparatus includes a strong NdFeB magnet ( = 450 ± 1 mT) capable of producing a magnetic field of 371 ± 1 mT at the surface of the anode.

Electrolysis Can Be Used to Resolve Hydrogenation Pathways at Palladium Surfaces in a Membrane Reactor.

For common hydrogenation chemistries that occur at high temperatures (where H is adsorbed and activated at the same surface which the substrate must also adsorb for reaction), there is often little consensus on how the reactions (e.g., hydro(deoxy)genation) actually occur.

Physical Separation of H Activation from Hydrogenation Chemistry Reveals the Specific Role of Secondary Metal Catalysts.

An electrocatalytic palladium membrane reactor (ePMR) uses electricity and water to drive hydrogenation without H gas. The device contains a palladium membrane to physically separate the formation of reactive hydrogen atoms from hydrogenation of the unsaturated organic substrate. This separation provides an opportunity to independently measure the hydrogenation reaction at a surface without any competing H activation or proton reduction chemistry.

An industrial perspective on catalysts for low-temperature CO electrolysis.

Electrochemical conversion of CO to useful products at temperatures below 100 °C is nearing the commercial scale. Pilot units for CO conversion to CO are already being tested. Units to convert CO to formic acid are projected to reach pilot scale in the next year.

Defining Direct Orbital Pathways for Intermolecular Electron Transfer Using Sensitized Semiconducting Surfaces.

High-performance electronic materials and redox catalysts often rely on fast rates of intermolecular electron transfer (IET). Maximizing IET rates requires strong electronic coupling () between the electron donor and acceptor, yet universal structure-property relationships governing in outer-sphere IET reactions have yet to be developed. For ground-state IET reactions, is reasonably approximated by the extent of overlap between the frontier donor and acceptor orbitals involved in the electron-transfer reaction.

π covalency in the halogen bond.

Halogen bonds are a highly directional class of intermolecular interactions widely employed in chemistry and chemical biology. This linear interaction is commonly viewed to be analogous to the hydrogen bond because hydrogen bonding models also intuitively describe the σ-symmetric component of halogen bonding. The possibility of π-covalency in a halogen bond is not contemplated in any known models.

Self-driving laboratory for accelerated discovery of thin-film materials.

Discovering and optimizing commercially viable materials for clean energy applications typically takes more than a decade. Self-driving laboratories that iteratively design, execute, and learn from materials science experiments in a fully autonomous loop present an opportunity to accelerate this research process. We report here a modular robotic platform driven by a model-based optimization algorithm capable of autonomously optimizing the optical and electronic properties of thin-film materials by modifying the film composition and processing conditions.