Suppressing reverse water-gas-shift (RWGS) reaction is high desirable but challenging and underdeveloped for Cu/ZnO catalysts, particularly for commercial Cu/ZnO/Al2O3 catalysts. Different from the current methodologies to reduce RWGS reaction, we report a simply surface silylation method for efficiently minimizing RWGS reaction over a commercial Cu/ZnO/Al2O3 catalyst. This method suppresses STYCO (Space-time yield) from 97.4 to 0.7 gCO·kgcat−1·h−1, improving STYMeOH from 20.2 to 39.9 gMeOH·kgcat−1·h−1 and methanol selectivity from 15.1 to 92.9 mol%. The combination of characterization methods and density functional theory calculations provide insight into the suppressing mechanism of surface silylation on catalyst. A hydroxyl (on ZnO)-promoted RWGS reaction cycle is discovered, which can be efficiently inhibited by the consuming of hydroxyls via surface silyation. Our results provide a way to regulate RWGS reaction on Cu/ZnO-based catalysts and are expected to the further use of silylation strategy to tune the interconversion of CO and CO2 via RWGS/WGS reaction on hydrogenation catalysts.

Despite their potential promise, multicomponent materials have not been actively considered as catalyst materials to date, mainly due to the massive compositional space. Here, targeting ternary electrocatalysts for fuel cells, we present a machine learning (ML)-driven catalyst screening protocol with the criteria of structural stability, catalytic performance, and cost-effectiveness. This process filters out only 10 and 37 candidates out of over three thousand test materials in the alloy core@shell (X3Y@Z) for each cathode and anode of fuel cells. These candidates are potentially synthesizable, lower-cost and higher-performance than conventional Pt. A thin film of Cu3Au@Pt, one of the final candidates for oxygen reduction reactions, was experimentally fabricated, which indeed outperformed a Pt film as confirmed by the approximately 2-fold increase in kinetic current density with the 2.7-fold reduction in the Pt usage. This demonstration supports that our ML-driven design strategy would be useful for exploring general multicomponent systems and catalysis problems.

The use of mixed metal oxide anodes in wastewater electrochemical treatment depends on the production of efficient, stable, and economically viable anodes. Thus, Ti/RuO2-TiO2 anodes were prepared by unconventional heating methods using a CO2 laser and microwave irradiation. The calcination method significantly modified the surface morphology, electronic structure, and electrocatalytic properties of the anodes. Compared with the conventionally-prepared anode, anodes made using laser and microwave display increase by approximately 2 and 3 times the voltammetric charge and decrease by 2.8 and 5.4 times the charge transfer resistance. Moreover, laser and microwave-prepared anodes presented a lifetime of 4.4 and 2.3 times longer than the furnace-prepared anode. High efficiency in generating hypochlorite is achieved in 1 h using a laser-prepared anode (372 mg L−1), which improves the degradation and mineralization of ciprofloxacin by electrolysis. After UVC-irradiation, the anode with the lowest energy consumption (7.14 kWh g–1TOC) was prepared by microwave radiation.

Rational design and fabrication of nonprecious metal-based electrocatalysts with high activity and excellent stability for overall water splitting (OWS) is still a grand challenge. Here we report a novel electrocatalyst constructed by incorporating molybdenum into the Ni3S4 lattices grown on carbonized wood (denoted as Mo-Ni3S4/CW). Experimental results and density functional theory (DFT)-based calculations demonstrate that lattice expansion of Ni3S4 caused by Mo doping optimizes adsorption energy of hydrogen/oxygen species and regulates local charge density of active sites, which promote the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Also, a nickel (oxy)hydroxide (Ni-OOH) layer generated via surface reconstruction of Ni3S4 nanosheets improves the intrinsic activity for OER. Moreover, the 3D low-tortuosity porous CW substrate increases the exposure of active specific surface, accelerates the rates of electron transfer, electrolyte diffusion, and gas products escaping. Accordingly, an optimized electrocatalyst (Mo-Ni3S4/CW-0.4) exhibits ultralow overpotentials of 17 and 240 mV for HER and OER at 10 mA cm−2, respectively. Besides, an electrolyzer composed of Mo-Ni3S4/CW-0.4 electrodes as both the anode and cathode shows a low cell voltage of 1.46 V at 10 mA cm−2 while maintaining superior durability over 50 h for OWS. Further, it requires only 0.19 V to achieve 10 mA cm−2 for hydrazine oxidation-assisted water electrolysis, indicating highly attractive potential for economical hydrogen production coupling with pollutants treatment.

The development of high-performance nonprecious metal catalysts that are resistant to water and poisoning is of great importance for industrial methane treatment and is challenging. Herein, we prepared a Co3O4/La2O2CO3/LaCoO3 heterostructure catalyst with excellent catalytic performance (T90 =476 °C), resistance to water and resistance to poisoning using a simple solvent-thermal method. DFT calculations combined with experimental characterization demonstrated that La2O2CO3 provides more reactive oxygen species (O- and O2-) to Co3O4 via charge transfer at the interface to enhance the oxidation of methane. Moreover, water and SO2 could be preferentially adsorbed on La2O2CO3 to protect the active site of Co3O4, which improved its poisoning tolerance. Correspondingly, the structure had more density states near the Fermi level and accelerated the electron transfer on the structural surface, which enhanced the adsorption and dissociation of oxygen and methane. This research provides a comprehensive understanding of the structure-performance relationship of heterogeneous structured catalysts in catalytic combustion.

Herein, we designed a C2+-producing catalyst by incorporating Lewis acid boron dopant into porous copper oxides nanotubes (B-CuO NTs) via a convenient electrospinning−calcination method. The B-CuO NTs catalyst achieved a 60.5% C2+ Faraday efficiency (FE) including 47% of ethanol, a 4-fold increase over CuO in a flow cell at − 0.6 V vs reversible hydrogen electrode (RHE). In situ characterizations demonstrate that the strong ability for *CO adsorption on B-CuO NTs facilitates the hydrogenation to the *CHO intermediate and promotes the C-C coupling further to *OCCHO intermediate via the proton-coupled electron transfer reactions. Theoretically calculations demonstrate that B doping induced polarized charge redistribution could suppress the *CHO transfer to C1 products by reducing the energy barrier for further OC-CHO coupling. This work provides a comprehensive understanding of Lewis acid B doping effect on regulating the C-C coupling pathway and improving the C2 selectivity.

Herein, biomass-derived activated carbon (bio-AC) was synthesized using rice husk as a biotemplate and natural carbon source. After immobilization of Ni, the supported Ni/bio-AC showed excellent catalytic activity in the pyrolysis of fatty acids to paraffin-based biodiesel in H2-free and solvent-free conditions, corresponding to the conversion of 99.6% and a total alkane yield of 95.1%, including 88.9% heptadecane. Based on comprehensive characterizations, the calculated turnover frequency of Ni/bio-AC was 3.9 times that of conventional Ni/AC. Significantly enhanced olefin selectivity was further obtained by N-doping of Ni/bio-AC, which was attributed to the inhibition of -COO* dissociation by the Ni-N sites. The possible catalytic reaction pathways from stearic acid to heptadecane via aliphatic alcohol as a reaction intermediate were investigated. Besides, efficient conversions of saturated and unsaturated plant oils were also achieved over Ni/bio-NAC catalysts in Py-GC/MS through pulsed catalytic pyrolysis manner, showing a promising prospect for sustainable biofuels and chemical production.

The electrocatalytic activity towards two electron oxygen reduction reaction of graphite felt was advanced by incorporating carbon nitride, carbon nanotubes and polytetrafluoroethylene through vacuum filtration, which prevented the cleavage of O-O bond, facilitated the charge transfer, and established more three-phase active sites. To ameliorate the oxygen transfer process, the configuration of side-aeration was proposed, providing forced convection to reduce the thickness of diffusion layer, and increasing the dissolved oxygen. By simplified combination of refining the orientation of gas flow and modified graphite felt, the dual-chamber configuration rendered a qualitative leap in H2O2 generation capacity to 4.44–6.89 mg h−1 cm−2. The alkaline affinity of developed system was discussed in terms of a beneficial outer-sphere electron transfer pathway, the variation on adsorption strength of oxygenated species and working electrode potential range. Finally, Long-term operation stability and successful application in Electro-Fenton indicated great potential of developed system for H2O2 synthesis and environmental remediation.

The in-depth mechanism of the emerging Ru-catalyzed polyolefin hydrogenolysis remains unclear. Here, we overcome this challenge by constructing a strong metal-support interaction (SMSI) system based on Ru/TiO2 catalysts. With the increase of SMSI intensity, electrons are transferred from the TiOx capping layer to the Ru species. This effect facilitates the key steps of hydrogenation/desorption, while having little effect on the dehydrogenation and C–C cracking elementary reactions. As a result, the catalyst with higher hydrogenation capability prone to proceed hydrogenation and desorption step, thus suppressing cascade C–C cracking and avoiding the production of low value methane. The catalyst with the strongest SMSI effect exhibits a liquid fuel yield of 89.4% at ~100% solid conversion. The SMSI effect also enables the catalysts with superior stability, so it can also efficiently upcycle commercial polyolefins. This work provides an in-depth understanding of the effects of metal-support interactions on polyolefin hydrogenolysis and paves the way for catalyst design.

It is economical to perform methane and carbon dioxide reforming under high-pressure and temperature conditions, but the harsh operation condition poses a grand challenge for coke-resistant catalyst design. We report herein that surface-segregation-free Co1Rh3 clusters are stable catalysts under 20 bars at 850 oC. Microkinetic analysis discloses that balanced and lowered surface coverages of C* and O* constitute the most abundant reaction intermediates on Co1Rh3 clusters at elevated pressures, with respect to that of the monometallic ones, thus avoiding surface carbon accumulation or surface oxidative deactivation. Moreover, density functional theory calculations of carbon atom nucleation discloses that adsorbed carbon transformation to refractory, graphene-like carbon is suppressed on Co1Rh3 cluster surface, owing to increased energetic barrier and ensemble size, hence, only CO2 gasifiable soft carbon could form. The revelation of the electronic/geometric features of Co1Rh3 is regarded to provide a guidance for future coke-resistant catalyst design.

The separation efficiency and migration rate of photogenerated carriers are important factors determining the activity of photocatalysts. In this work, CN/CNQDs were prepared by self-introducing carbon nitride quantum dots (CNQDs) into the planar structure of carbon nitride (CN) using a novel photo-triggered self-assembly strategy. Different from conventional interfacial modification strategies based on van der Waals forces or hydrogen bonding, CN/CNQDs atomic junctions formed chemical bonds between the two components, which have stronger interfacial interactions and facilitate efficient carrier migration between the two components. The continuous π-conjugated structure of CN/CNQDs also provided unique conditions for carrier migration. In addition, the presence of in-plane electric field (IEF) in CN/CNQDs acted as a direct driving force for the migration of electrons and holes in the opposite directions, which greatly facilitates the separation and transfer of photogenerated carriers in CN/CNQDs. This work provides an atomic-level strategy for the construction of heterojunction photocatalyst systems.

Defects engineering in nanomaterials can be used to precisely and effectively modulate catalysts’ reactivity. Here we report a highly efficient NH3-SCR catalyst constructed with in-situ formation of carbon-doped CeZrO2−x with dual defects, in which O atoms are substituted by C atoms to generate surface oxygen vacancies and subsurface oxygen substitutions. The carbon-doped CeZrO2−x exhibit superior activity and better SO2/H2O resistance compared with traditional bulk CeZrOx and V2O5-WO3/TiO2. The related characterization results reveal that the surface oxygen vacancy and subsurface oxygen substitution resulted in the formation of a large number of unsaturated coordination Ce and Zr species on catalyst’s surface, which contributed to the adsorption and activation of NH3, thus promoting the catalytic activity. Meanwhile, the abundant oxygen vacancy also stimulated the E-R reaction pathway over carbon-doped CeZrO2−x. In addition, it was proved that more zirconium sulfate and unstable ammonium sulfate species were exposed over carbon-doped CeZrO2−x, benifiting the better SO2-tolerance.

Abstract not available

Reductive methods of polyolefin waste deconstruction such as hydrogenolysis/hydrocracking have enabled advances in plastic upcycling at low temperatures. However, these processes require hydrogen gas, presenting economic and environmental tradeoffs. Here, we present an overview of recent developments in low-temperature, hydrogen-free depolymerization of polyolefins. We start by introducing technologies that utilize sacrificial solvents to cleave C-C bonds, followed by progress in solvent-free depolymerization. We then provide an overview of catalytic processes in petroleum and lignin upgrading that may be extended to polyolefin activation and depolymerization, including alkane dehydrogenation/aromatization, transfer hydrogenation, and hydrogen co-generation, as well as opportunities for utilizing the polymer itself as a hydrogen source. Next, we provide an overview of techniques for quantifying reaction progress via hydrogen consumption and for characterizing the degree of unsaturation of polyolefins. We close with an outlook on the role of feedstock treatment, economic analysis, and process optimization in ushering in these new technologies.

In the context of global warming and atmospheric methane growth, photo-assisted total oxidation of methane is of great importance to diminish greenhouse effect. However, catalytic oxidation of methane at ambient conditions remains a formidable challenge because of its high structure stability. Herein, we report a highly active and stable NiO nanocrystalline decorated on ZnO-CoNi solid solution (NiO/ZnO-CoNi) catalyst which enables 88 % photocatalytic conversion of methane to CO2 and H2O under ambient conditions to maintain a continuous reaction. The unprecedented photocatalytic performance of NiO/ZnO-CoNi originates from the high mobility of surface lattice oxygen of supported NiO nanocrystallines driven by the photogenerated electrons and internal electric field of ZnO-CoNi solid solution. More importantly, the methane conversion of NiO/ZnO-CoNi remains higher than 37 % even when the methane concentration is up to 5000 ppm, showing promise for methane elimination applications in the vicinity of large methane emission sources.

Efficient refractory organic compound (ROC) removal through Ti4O7 ceramic membrane in electrochemical advanced oxidation processes (EAOPs) requires high electrochemical reactivity and stability. Herein, we report on the synthesis and properties of Ti3C2 MXene-doped Ti4O7 ceramic membranes (Ti3C2@Ti4O7) using a spark plasma sintering system, after employing density functional theory calculations to design the electrocatalyst. Doping with Ti3C2 MXene resulted in interfacial Ti–O–Ti chemical bond formation, which greatly improved the electronic structure and the generation of hydroxyl radicals (•OH). Compared with pristine Ti4O7, the charge-transfer resistance of Ti3C2@Ti4O7 decreased from 59.09 to 4.21 Ω, and the •OH generation rate enhanced 2.3 − 2.6-fold. Ti3C2@Ti4O7 could effectively remove 1,4-Dioxane from natural groundwater, and the residual 1,4-Dioxane concentration met the requirements for drinking water. Our study provides a proof-of-concept demonstration using Ti3C2 MXene to manufacture a doped Ti4O7 ceramic membrane for effective ROC removal. The theoretical predictions from this study can inspire novel electrocatalyst designs for EAOPs.

The electrocatalytic nitrogen reduction reaction (ENRR) has been identified as a promising method for environmentally friendly NH3 production under ambient conditions. The interfacial electric field has been found to hold significant potential for enhancing ENRR performance. The as-prepared WO3-C3N4-R catalyst exhibited a promising NH3 yield of 43.5 µg h−1 mgcat−1 and a high FE of 11.2 % in 0.1 M Li2SO4. DFT calculations indicate that the enlarged Fermi level can induce more electrons transfer from WO3 to C3N4 to form a strong interfacial electric field. In situ Raman and FTIR spectra demonstrate that the engineered intensified interfacial electric field in WO3-C3N4-R can enhance the adsorption of N2 molecules by forming strong W-N bonds and the polarization of NN bond through an "acceptance-donation" mechanism, resulting in a promoted ENRR kinetics. This work demonstrates a novel strategy to design NERR catalysts and provides insights into the effects of interfacial electric field on NERR.

Three-dimensional ZnO/CuO nanoforests (NFRs) were fabricated via the galvanic submerged photosynthesis of crystallites in water at ambient temperature and pressure, and their photoelectrochemical (PEC) properties and applicability to microbial PEC (MPEC) cells were evaluated. ZnO/CuO NFRs irradiated with UV light for 48 h showed a high PEC current of − 2.9 ± 1.3 mA/cm2 and hydrogen (H2) generation rate of 0.63 ± 0.29 µmol/cm2/day at 0 V vs. RHE owing to their superior light absorption, large BET specific surface area, and low charge recombination. The biocompatibility of the ZnO/CuO NFRs was evaluated by assessing their influence on Escherichia coli MG1655 growth. The ZnO/CuO NFRs leached Cu2+ and inhibited bacterial growth after immersion in the medium. Cu elution could be prevented by maintaining the potential at 0.01 V vs. RHE. The ZnO/CuO NFRs can be used as photocathodes for PEC H2 generation and the MPEC-based synthesis of valuable CO2-reduction products.

A DFM has been designed for direct air capture of CO2 and in situ catalytic methanation for sustainable natural gas production. It is composed of 1% Ru, 10% “Na2O”/γ-Al2O3//ceramic monolith, the latter with high open frontal area to reduce pressure drop when processing real air. Extended laboratory aging was conducted using simulated ambient capture conditions varying in temperature and humidity for over 100 cycles (450+ hours on stream). The continuous test protocol was designed to simulate some representative ambient conditions expected during advanced pilot plant testing. The capture step was followed by catalytic hydrogenation of CO2 to methane during a temperature swing to 300°C. Results demonstrated stable, repeatable CO2 capture and CH4 production with no evidence of sorbent or catalyst deactivation. These findings support the case for further advanced testing to substantiate scale up of this material for producing a useful fuel or feedstock while mitigating climate change.

Thermocatalytic conversion of CO2 into liquid fuels and chemicals is a promising approach to mitigate global warming. Although, the CO2 conversion and long-chain hydrocarbon selectivity are highly dependent on the choice of metal-oxide promoter, but role of the promoter remains unclear. Herein, the role of MgO as a promoter for an Fe-based catalyst was investigated. Bimetallic Na-FeMgOx catalyst exhibited a high C5+ yield of 25.1% with a CO2 conversion of 49.1% at the early stage of the reaction. The presence of MgO facilitates the reduction of Fe oxides and formation of oxygen vacancies by transferring electrons to Fe-based phases. In addition, at the early stage of reaction, the decoration of the Mg oxide surface with nanosized χ-Fe5C2 enhances the C5+ yield. However, the progressive transformation of MgO to MgCO3 during CO2 conversion deactivates the Na-FeMgOx catalyst. A detailed deactivation mechanism is also discussed.