Catalyst-Free Carbon Dioxide Conversion in Water Facilitated by Pulse Discharges

Saccharomyces cerevisiae inactivation during water disinfection by underwater plasma bubbles: Preferential reactive species production and subcellular mechanisms

The escalating challenges posed by water resource contamination, especially exacerbated by health concerns associated with microbial fungi threats, necessitate advanced disinfection technologies. Within this context, non-thermal plasma generated within bubble column reactors emerges as a promising antifungal strategy. The effects of direct plasma bubbles within different discharge modes and thus-produced plasma activated water (PAW) on the inactivation of Saccharomyces cerevisiae are investigated. Results show that plasma bubbles generated by dielectric barrier discharge (DBD) mode can effectively inactivate yeast cells (∼4.44 logs reduction) within 1 min, outperforming the spark discharge (SD). In this case, SD can cause a significant portion of cell necrosis, possibly due to the high electric field at the bubble interface. In PAW, DBD and SD produce different dominant long-lived oxygen and nitrogen species, while the crucial short-lived species in yeast apoptosis are both attributed to the singlet oxygen (1O2) as confirmed by scavenger tests. The detection of intracellular reactive oxygen species and antioxidant enzymes further illustrates the role of PAW in triggering apoptosis. Overall, this study demonstrates the discharge mode-dependent modulation of reactive species chemistry in plasma-liquid interactions and provides new insights into the subcellular mechanism of plasma-enabled yeast inactivation for water resource decontamination.

Promoting Alcohols Electrooxidation Coupled with Hydrogen Production via Asymmetric Pulse Potential Strategy

Electrocatalytic organic oxidation coupled with hydrogen (H2) production emerges as a profitable solution to simultaneously reduce overall energy consumption of H2 production and synthetic high-value chemicals. Noble metal catalysts are highly efficient electrocatalysts in oxidation reactions, but they deactivate easily weakening the benefit in actual production. Herein, we report a universal asymmetric pulse potential strategy to achieve long-term stable operation of noble metals for various alcohol oxidation reactions and noble metal catalysts. For example, by pulsed potentials between 0.8 V and 0 V vs. RHE, palladium (Pd)-catalyzed glycerol (GLY) electrooxidation can continuously proceed for more than 2800 h with glyceric acid (GLA) selectivity of >70 %. Whereas, Pd electrocatalyst becomes nearly deactivated within 6 h of reaction under conventional potentiostatic strategy. Experimental and theoretical calculation results reveal that the generated electrophilic OH* from H2O/OH- oxidation on Pd (denoted as Pd-OH*) acts as main active species for GLY oxidation. However, Pd-OH* is prone to be oxidized to PdOx resulting in performance decay. When a short reduction potential (e.g., 0 V vs. RHE for 5 s) is powered, PdOx can be reversibly reduced to restore the current. Moreover, we tested the feasibility of this strategy in a flow electrolyzer, verifying the practical application potential.

Foam-like Porous Structured Trimetal Electrocatalysts Exhibiting Superior Performance for Overall Water Splitting and Solid-Liquid Zinc-Air Batteries

Electrocatalysts through an interconnected porous structure that are highly durable, active, and affordable for industrial scale production are necessary for electricity conversion and storage devices with superior effectiveness. In the present study, we synthesized free-standing tri-metal oxide (FeNiCoO4) on top of an incredibly interconnected foam-like porous structure (FNCO) via a simple method. The enhanced FNCO-600 showed remarkable electrocatalytic activity and outstanding stability to the related half-cell responses with regard to oxygen reduction reaction (ORR = 0.757 V), oxygen evolution reaction (OER = 230 mV), and hydrogen evolution reaction (HER = 211 mV). Additionally, we looked into the overall efficiency of water splitting using the FNCO-600 catalyst, which exhibited exceptional longevity (70 h) and an impressive cell voltage (1.72 V). Furthermore, using FNCO-600 as the cathode, we created rechargeable solid-liquid electrolyte-based Zn-air batteries that demonstrated enhanced power densities of 21.8 mW cm-2 and 167.4 mW cm-2 with noteworthy durability. Finally, we showed how to synthesize and produce free-standing, foam-like porous structure catalysts on an industrial scale that provide excellent energy storage and conversion.

Crystalline-Amorphous Interfaces Engineering of CoO-InOx for Highly Efficient CO2 Electroreduction to CO

As a fundamental product of CO2 conversion through two-electron transfer, CO is used to produce numerous chemicals and fuels with high efficiency, which has broad application prospects. In this work, it has successfully optimized catalytic activity by fabricating an electrocatalyst featuring crystalline-amorphous CoO-InOx interfaces, thereby significantly expediting CO production. The 1.21%CoO-InOx consists of randomly dispersed CoO crystalline particles among amorphous InOx nanoribbons. In contrast to the same-phase structure, the unique CoO-InOx heterostructure provides plentiful reactive crystalline-amorphous interfacial sites. The Faradaic efficiency of CO (FECO) can reach up to 95.67% with a current density of 61.72 mA cm-2 in a typical H-cell using MeCN containing 0.5 M 1-Butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) as the electrolyte. Comprehensive experiments indicate that CoO-InOx interfaces with optimization of charge transfer enhance the double-layer capacitance and CO2 adsorption capacity. Theoretical calculations further reveal that the regulating of the electronic structure at interfacial sites not only optimizes the Gibbs free energy of *COOH intermediate formation but also inhibits HER, resulting in high selectivity toward CO.

Low-coordinated copper facilitates the *CH2CO affinity at enhanced rectifying interface of Cu/Cu2O for efficient CO2-to-multicarbon alcohols conversion

The carbon-carbon coupling at the Cu/Cu2O Schottky interface has been widely recognized as a promising approach for electrocatalytic CO2 conversion into value-added alcohols. However, the limited selectivity of C2+ alcohols persists due to the insufficient control over rectifying interface characteristics required for precise bonding of oxyhydrocarbons. Herein, we present an investigation into the manipulation of the coordination environment of Cu sites through an in-situ electrochemical reconstruction strategy, which indicates that the construction of low-coordinated Cu sites at the Cu/Cu2O interface facilitates the enhanced rectifying interfaces, and induces asymmetric electronic perturbation and faster electron exchange, thereby boosting C-C coupling and bonding oxyhydrocarbons towards the nucleophilic reaction process of *H2CCO-CO. Impressively, the low-coordinated Cu sites at the Cu/Cu2O interface exhibit superior faradic efficiency of 64.15  ±  1.92% and energy efficiency of ~39.32% for C2+ alcohols production, while maintaining stability for over 50 h (faradic efficiency >50%, total current density = 200 mA cm-2) in a flow-cell electrolyzer. Theoretical calculations, operando synchrotron radiation Fourier transform infrared spectroscopy, and Raman experiments decipher that the low-coordinated Cu sites at the Cu/Cu2O interface can enhance the coverage of *CO and adsorption of *CH2CO and CH2CHO, facilitating the formation of C2+ alcohols.

Long-Chain Hydrocarbons from Nonthermal Plasma-Driven Biogas Upcycling

The burgeoning necessity to discover new methodologies for the synthesis of long-chain hydrocarbons and oxygenates, independent of traditional reliance on high-temperature, high-pressure, and fossil fuel-based carbon, is increasingly urgent. In this context, we introduce a nonthermal plasma-based strategy for the initiation and propagation of long-chain carbon growth from biogas constituents (CO2 and CH4). Utilizing a plasma reactor operating at atmospheric room temperature, our approach facilitates hydrocarbon chain growth up to C40 in the solid state (including oxygenated products), predominantly when CH4 exceeds CO2 in the feedstock. This synthesis is driven by the hydrogenation of CO2 and/or amalgamation of CHx radicals. Global plasma chemistry modeling underscores the pivotal role of electron temperature and CHx radical genesis, contingent upon varying CO2/CH4 ratios in the plasma system. Concomitant with long-chain hydrocarbon production, the system also yields gaseous products, primarily syngas (H2 and CO), as well as liquid-phase alcohols and acids. Our finding demonstrates the feasibility of atmospheric room-temperature synthesis of long-chain hydrocarbons, with the potential for tuning the chain length based on the feed gas composition.