Abstract Proton exchange membrane water electrolysis (PEMWE) requires anode catalysts that sustain acidic oxygen evolution in practical stacks with minimal noble-metal content. Cobalt spinel oxides are cost-attractive but dissolve rapidly in acid as cobalt sites over-oxidize under anodic bias. Here we show that incorporation of d10-configured p-block cations (Sb, Ge, In, and Ga) into Co3O4 stabilizes cobalt sites by promoting robust heterometallic Co–O–M interactions. Density functional theory predicts dopant-driven charge redistribution that suppresses over-oxidation of octahedral Co while maintaining favorable binding of oxygen intermediates. Operando Co K-edge X-ray absorption and time-resolved dissolution measurements confirm reduced oxidation-state dynamics and cobalt loss, whereas a d-block d10 control (Zn) shows no such stabilization. In a PEMWE single cell at 80 °C, Sb/Co3O4 reaches >3500 mA cm–2 at 2.0 V and operates for >1000 h at 250 mA cm–2. This work establishes p-block d10 incorporation as a general route to iridium-free PEMWE anodes.
Abstract The morphology and microenvironment of ion-conducting polymers (ionomers) on the catalyst electrode surface critically govern the CO2 electrocatalytic performance. Herein, we report a dual-reconstruction strategy that synergistically tailors the surface structure of the Nafion ionomer using positively charged molecules and solvent effect. By combining a low-dielectric-constant solvent (isopropanol) with arginine cations, the optimized electrode achieves an 83.6% Faradaic efficiency for multicarbon (C2+) products at a high current density of –500 mA cm–2 in 1 M KOH. Based on experimental characterization and MD simulations, we propose a structural model in which the Nafion side chains are oriented away from both the catalyst surface and the electrolyte phase. In situ spectroscopic analyses, theoretical calculation, and experimental evidence suggest that this structural reorganization disrupts the interfacial hydrogen-bonding network, suppresses the competing hydrogen evolution reaction, improves effective gaseous CO2 accessibility, and facilitates C–C coupling along an energetically favorable *OC–COH pathway. This work provides valuable insights into microenvironment engineering of ionomer–catalyst interfaces for efficient CO2 electrolysis.
Abstract Polyolefin hydrocracking over Brønsted acidic ZSM-5 produces light hydrocarbons with narrow product distributions, but further increases in propane and butane selectivity are required to improve process economics and sustainability. Here, we examined the effect of various metal and metal oxide dopants, namely Pt, Pt-Sn, SnOx, ZnOx, and GaOx, on ZSM-5-mediated polyolefin hydrocracking and identified GaOx as a selective promoter for light gas formation. Incorporation of gallium oxide (3 wt % Ga) was shown to increase propane selectivity from 40 c-wt %, achieved over ZSM-5, to near 60 c-wt %, reaching a combined propane and butane selectivity of 85 c-wt %, while maintaining solids conversion. To elucidate the role of gallium oxide, we used ex situ and operando characterization techniques to probe acidity, local coordination environment, and the spatial distribution of GaOx species. Extra-framework gallium oxide introduced via incipient wetness impregnation reduced the measured acid site density from 1275 to 911 μmol g–1, decreased the Brønsted/Lewis acid site ratio, and formed a high-coverage GaOx layer on the external surface of the zeolite. Operando experiments show that Ga is present in both Ga3+ and Ga1+ under reaction conditions. Attempts to disperse gallium oxide through reductive pretreatments led to an increase in the Lewis acid site concentration and a 10 c-wt % decrease in propane selectivity, highlighting the importance of the specific location, structural, and acidic configurations. Systematic variation of impregnation methods to control location and dispersion revealed a synergistic interaction between gallium oxide and zeolite acid sites, with propane selectivity strongly influenced by spatial proximity of GaOx to acid sites. Furthermore, vapor-phase flow reactions with a model compound demonstrated a decrease in intermediate product formation compared to the zeolite alone. The optimized catalyst was validated across diverse polyolefin substrates and resulted in similar increases to propane selectivity, yielding >80 c-wt % combined C3–C4 selectivity across the range of polyolefin substrates.
Abstract Efficient H2 dissociation and subsequent spillover of active hydrogen species are critical factors for achieving high activity in CO2 hydrogenation reactions. Herein, we constructed a well-designed and highly dispersed Cu–In bimetallic catalyst supported on CeO2. This catalyst enables the spatial separation of plasmonic enhancement, H2 activation, and CO2 conversion sites, thereby significantly improving H2 dissociation capability and H-spillover efficiency. Comprehensive investigations using multiple transient characterizations, together with in situ/operando spectroscopy, reveal that the three components are tightly coupled through H-spillover, electron transfer, and interfacial interactions. Specifically, the Ce sites on the CeO2 surface serve as the active centers for CO2 conversion via a redox mechanism, while the available indirect but consistent evidence suggests that In species likely act as the primary H2 dissociation sites, promoting the reduction of Cu species and the regeneration of oxygen vacancies on the CeO2 surface through H-spillover. Meanwhile, the localized surface plasmon resonance (LSPR) effect of Cu significantly enhances the light absorption and photothermal conversion efficiency of the catalyst. The photoexcited LSPR electrons generated by Cu are further transferred to the In species and CeO2 surface, thereby facilitating H2 dissociation and the redox cycling of Ce sites. Such a “functional separation–synergistic enhancement” strategy effectively improves the catalytic activity, and the optimal catalyst achieves a CO yield of 230.1 mmol gcat–1 h–1 W–1 cm2 under 1.5 W cm–2 light irradiation at the surface temperature of 300 °C, significantly outperforming both the corresponding dark reaction and the monometallic Cu/CeO2 and In/CeO2 counterparts. This work provides important design principles and mechanistic insights for constructing highly active CO2 hydrogenation catalytic systems by enhancing H2 dissociation and H-spillover processes.
Abstract Chemical fixation of CO2 with CH3OH into value-added chemicals, such as dimethyl carbonate (DMC), plays a crucial role in carbon neutrality and resource recycling. However, its efficiency is limited by the ineffective synergistic activation of CO2 and CH3OH. Here, we employ a strategy to construct CeO2-CePO4 heterojunctions by phosphate-functionalized CeO2, introducing an asymmetric Ceδ+-O-P structure for CO2 and CH3OH activation. The prepared Ce0.8P0.2Oσ catalyst achieves a CH3OH conversion of 28.6% with nearly 100% DMC selectivity and retains its performance for 300 h during continuous DMC synthesis at 140 °C. Experimental characterization supports the formation of local Ceδ+-O-P sites in the catalyst. DFT calculations based on one selected idealized strained model containing a specific local Ceδ+-O-P site show a distinct Bader charge for Ce–O–P and Ce–O–Ce coordinated oxygen atoms within this model. Within the same model, the local Ceδ+-O-P site is associated with elongation of the C–O bond in CH3O* and a lower energy barrier for its dissociation into *CH3 and *O, providing a model-specific interpretation of the enhanced DMC yield. This work develops a design strategy for asymmetric catalytic site via composite oxide heterojunctions engineered for CO2 and CH3OH activation, exhibiting great potential for large-scale continuous CO2 chemical fixation to high-value-added chemicals.
