Guohua Jing

This graphical abstract summarizes SO ₂ -poisoning mechanisms and resistance strategies for noble and non-noble metal CO oxidation catalysts.

Ammonia-fueled engines offer a route to transport decarbonization but require efficient removal of toxic NH3 slip. Water-rich exhaust inhibits selective NH3 oxidation over Cu/SSZ-13 through competitive H2O adsorption at Cu2+ sites. Here, a defect-rich CeO2 shell is constructed around Cu/SSZ-13 to regulate water adsorption and preserve Cu2+-bound NH3. The core-shell catalyst achieves complete NH3 conversion near 225 °C, approximately 50 °C below that required by Cu/SSZ-13. At 225 °C, it maintains NH3 conversions of approximately 65% and 60% in 10 and 20 vol% H2O, respectively, compared with 36% and 20% over Cu/SSZ-13, while retaining N2 selectivity above 90%. Mechanistic evidence supports a Cu-mediated internal selective catalytic reduction (i-SCR) pathway, in which NOx-derived intermediates formed by partial NH3 oxidation react with the remaining adsorbed NH3 to produce N2. Under dry conditions, Ce3+-associated Lewis acid sites in the shell increase the Lewis-bound NH3 population available for this reaction, enhancing low-temperature activity. Under humid conditions, D2O-DRIFTS supports the formation of water-derived hydroxyls on the CeO2 shell, while DFT calculations identify oxygen vacancies as favorable sites for H2O dissociation and hydroxyl stabilization. These hydroxyls passivate strongly water-binding sites, suppressing further molecular H2O adsorption and limiting water-vapor entry into the Cu/SSZ-13 core. This mechanism alleviates competitive H2O adsorption at intrapore Cu2+ sites, thereby preserving their coordinated NH3 population and sustaining the i-SCR cycle. These findings provide a catalyst design strategy for low-temperature NH3 slip removal from ammonia-fueled engine exhaust, combining resistance to water inhibition with high N2 selectivity.

Acidic CO2 electrolysis reduction (ECO2RR) mitigates carbonate formation but exposes the cathode to proton-driven hydrogen evolution; selectivity depends on electrolyte cations accumulated in the electric double layer (EDL), which restrict proton transport. Studies of ECO2RR on Bi based catalysts largely correlate operando-generated reconstructed solid structures with activity, leaving unresolved how lattice anions released during reconstruction alter the EDL. Using BiPO4 as a model precursor, we decouple the contributions of reconstructed Bi and precursor-derived phosphate. Electroreduction near -0.9 V versus RHE forms Bi clusters on residual BiPO4 while releasing phosphate. The reconstructed Bi/BiPO4 solid provides charge-polarized Bi cluster sites that optimize *OCHO-pathway energetics, whereas released phosphate remains in adjacent K+-rich Helmholtz region rather than acting as a spectator. By associating with hydrated K+, precursor-derived phosphate increases the population and spatial compactness of interfacial K+ and reorganizes cation hydration and near-surface water. This anion-modified Helmholtz layer suppresses HER while facilitating water-mediated proton transfer and *OCHO hydrogenation through second-sphere electrostatic and solvation effects. Electrolyte-exchange experiments verify that removing releasable interfacial phosphate decreases the formic-acid Faradaic efficiency from 94.4% to 86.3% and simultaneously reduces the current density. These results expand catalyst reconstruction to the coupled evolution of the active phase and adjacent ion layer, identifying precursor-derived anions as interfacial design variables.

Corrosion of metallic equipment is a key challenge in amine-based CO2 capture processes. In this study, the corrosion behavior of 20# carbon steel in a non-aqueous ionic-liquid-based deep eutectic solvent, [AEP][Pro]-ethanol, was investigated and compared with that in conventional 30 wt% MEA using weight-loss tests, electrochemical measurements, surface characterization, contact angle analysis, and quantum chemical calculations. The results showed that [AEP][Pro]-ethanol exhibited much lower corrosiveness than MEA, especially under CO2-saturated conditions. The corrosion rate in CO2-saturated [AEP][Pro]-ethanol was 0.0332 mm·a-1, far lower than that in CO2-saturated MEA, 0.2303 mm·a-1. Electrochemical results indicated lower corrosion current and higher interfacial resistance in [AEP][Pro]-ethanol, while SEM, EDS, and XRD analyses confirmed severe corrosion and FeCO3 formation in CO2-saturated MEA but no obvious crystalline corrosion products in the [AEP][Pro]-ethanol system. The lower corrosion tendency of [AEP][Pro]-ethanol is attributed to its alkyl carbonate-dominated CO2 absorption products, reduced water activity, weaker cathodic depolarization, and possible interfacial adsorption of solvent components on the steel surface. These results demonstrate the potential of [AEP][Pro]-ethanol as a low-corrosion absorbent for CO2 capture.

To address the challenges of high desorption temperatures and excessive regeneration energy consumption in conventional organic amine absorbents, a novel functionalized ionic liquid-based ternary water-lean absorbent, [DBAPA][52AMP]-Ethanol-H2O, was proposed for efficient CO2 capture. This novel absorbent not only demonstrated excellent absorption performance, achieving a CO2 loading of 1.03 mol·mol–1, but also could be regenerated at a low temperature of 371 K, with a regeneration efficiency of 94%. The heat duty was estimated as 2.12 GJ·t–1 CO2, representing a 43.8% reduction compared to the benchmark MEA solution. Mechanistic studies using 13C NMR revealed that the dominant reaction during absorption–desorption is the conversion of carbamate to ethyl carbonate in the presence of ethanol, with minimal hydrolysis due to the low water content. This reaction pathway facilitated easier desorption and reduced regeneration energy consumption. The proposed reaction mechanism involves the initial formation of a zwitterion between the cation and CO2, followed by deprotonation of the cation, transferring the proton to the tertiary amine in the anion. Deprotonation was found to be the rate-limiting step, and its low activation energy barrier allows for efficient desorption at low temperature. This work offers valuable insights into the development of ionic liquid-based water-lean absorbents for industrial carbon capture, integrating low energy consumption, high efficiency, and excellent recyclability.

Volatile organic compounds (VOCs) are key precursors of ozone and secondary organic aerosols and pose serious risks to human health. Consequently, stringent emission abatement is urgently required under realistic operating conditions such as low inlet concentrations, high gas hourly space velocities, and high humidity. Catalytic oxidation is widely regarded as one of the most competitive end-of-pipe technologies. However, low-temperature operation remains kinetically challenging. Oxygen activation is sluggish, reaction intermediates can bind strongly, and catalysts are prone to deactivation by water, chlorine/sulfur-containing species, and carbonaceous deposits. Single-atom catalysts (SACs) provide an atomic-level platform in which isolated metal centers exhibit unique electronic structures and metal–support interfacial chemistry. These features can fundamentally reshape oxygen activation and VOC oxidation pathways. This review summarizes recent advances in SACs for low-temperature VOC oxidation and discusses how anchoring motifs (M–Ox, M–Nx, and defect-localized sites), support redox properties, and microenvironmental factors (hydroxyls and hydrophilicity) synergistically regulate oxygen delivery (adsorbed oxygen vs lattice oxygen), intermediate evolution (formate/benzoate/carbonate species), and conversion stability. Finally, perspectives are provided on future design and application of single-atom catalysts.