The control of volatile organic compounds (VOCs) from cooking oil fumes via synergic photothermocatalytic oxidation not only saves energy, but also helps to reduce carbon emissions. Differences between the copper oxide−ceria (CC) supported atomically-dispersed (Pt1/CC) and particulate Pt (PtNPs/CC) on photothermocatalytic heptane oxidation were investigated. The conversion efficiency at 170 oC of heptane oxidation over the Pt1/CC catalyst was 55% higher than that over the PtNPs/CC catalyst. PtNPs/CC showed a larger capacity of heptane adsorption, but limited amounts of the adsorbed oxygen and active surface lattice oxygen species were difficult to completely oxidize the over-adsorbed heptane. Heptane and its intermediates gradually accumulated at the active sites, resulting in poor catalytic activity and stability. However, Pt1/CC possessed a strong electron donating ability due to its unique coordination unsaturated sites and electron structure, which was conducive to oxygen activation. This allowed rapid conversion of heptane and intermediates, accelerating oxidation of the adsorbed heptane to CO2 and H2O. The complete oxidation of 500 ppm heptane was basically achieved at 190 oC and an optical power density of 300 mW/cm2.

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.

Industrial lignin mostly contains sulfur, which poisons metal catalysts easily. Metal sulfides with good S-resistance could be used as efficient catalysts for lignin oxidation, while metal sulfides preparation involved corrosive H2S. Here in, we proposed H2S-free fabrication of bimetallic Fe-ZnS/NC by industrial lignin self S-doping. The Fe-ZnS/NC 650 exhibited efficient oxidation activity (> 99% conversion) for β-O-4 cleavage and good S-resistance for industrial lignin oxidation. Density functional theory revealed the synergistic effect of FeS and ZnS in lignin oxidation, where FeS tended to activate O2 into superoxide radical (O2-•) and ZnS contributed to the polarization of β-O-4. The dual sites greatly reduced the migration distance of O2-• to the polarized β-O-4, facilitating the C-O/C-C cleavage. Hence, Fe-ZnS/NC 650 selectively converted lignin into carbonyl-containing aromatics with up to 92% selectivity under alkaline-free condition. This work developed a novel strategy using lignin-derived metal sulfide without external sulfur source for efficient lignin degradation.

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.

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.

Single-atom catalysts (SACs) have been widely used in Fenton-like water treatment, but studies on the selective induction of H2O2 to produce singlet oxygen (1O2) are rare. Herein, a carbon nitride supported high-loaded single-atom Cu-N3 catalyst (Cu-CN, Cu load is 15.46 wt%) is prepared to activate H2O2 to selectively form 1O2. Experimental and DFT calculation results reveal that the key factor for 1O2 production is the Cu-N3 coordination structure. Specifically, Cu-N3 coordination structure is conducive to decomposing H2O2 into·OOH/·O2-. Besides, the density of Cu-N3 sites is another key factor, high Cu-N3 site density is conducive to the rapid conversion of·OOH/·O2- to 1O2. Benefitting from the dominant role of 1O2, the Fenton-like degradation performance of Cu-CN/ H2O2 system is not disturbed under high salinity conditions, and the performance is significantly enhanced at high pH. This work represents an important reference in understanding SACs for activated H2O2 to generate 1O2.

Converting polymer waste to marketable products is a promising method to incentivize the development of competitive waste upcycling processes. Polyvinyl chloride (PVC) waste streams pose a unique challenge in this regard because of the presence of Cl atoms in the molecule. To address this issue, we report here a method to upcycle PVC plastics and produce a polyethylene wax in a mixed amine-water system, using hydrogen and a heterogeneous catalyst. We demonstrate that alkylamines as homogeneous catalysts and as Cl- sequestration media successfully dechlorinate PVC to a polyene, which is hydrogenated over a Pt/C heterogeneous catalyst. At optimal conditions, hydrocarbon wax yields greater than 70 % with melt temperatures above 80 °C were achieved. We use X-ray tomography to illustrate the PVC dissolution and reaction and quantify the product by differential scanning calorimetry (DSC). Characterization of the product reveals complete dechlorination and hydrogenation, as well as partial C-C bond scission, indicating a product similar to polyolefin adhesive waxes.

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.

Achievement of an efficient and stable electrocatalytic glycerol oxidation reaction (EGOR) is limited by a lack of strategies for designing advanced electrocatalysts that satisfy the desired product selectivity, high electrocatalytic activity, and stability. Here, we report that the reaction pathway of EGOR can be modulated by the incorporation of amorphous antimony oxide (SbOx) on the surface of a Pt nanoparticle electrocatalyst (SbOx-Pt), which creates highly selective glycerol oxidation to dihydroxyacetone (DHA), one of the most valuable products of EGOR. The selective control of adsorption behaviors of glycerol oxidation products allows for SbOx to act as a reaction pathway modulator. Moreover, SbOx deposition on a Pt surface also enhances the stability, electrocatalytic activity, and glycerol conversion of the Pt electrocatalyst, and thus promotes the EGOR. As a result, the SbOx-Pt electrocatalyst achieves a high DHA selectivity of 81.1%, which is about 11 times higher than that of commercial Pt/C electrocatalysts.

Two-dimensional layered carbon-coated FexSey nanocrystal superlattices with different crystalline structure (2D FexSey@C NS) are prepared and tested in Fenton-like reaction via PMS activation. The intrinsic nature and properties that govern the activity of 2D FexSey@C NS are deeply elucidated. Experimental analysis and theoretical calculations indicated that the spin state of Fe strongly decided the catalytic activity of 2D FexSey@C NS, and that a high spin state of Fe (4.16 μB) with a large effective magnetic moment not only regulated PMS adsorption (−3.06 eV) for increasing electronic density (0.79 e), but also accelerated interfacial charge transfer for HSO5− decomposition to produce SO4•−. Therefore, among 2D FexSey@C NS, 2D FeSe2 @C NS exhibited the most active performance in PMS activation with brilliant durability and adaptability. The study illustrates a new application of superlattice nanomaterials in environmental remediation and supplies fundamental insight to the intrinsic chemical structure of Fe-based catalysts for PMS activation.

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.

Photocatalytic hydrogen evolution from water vapor presents a novel approach to solar energy conversion. Nevertheless, the design and synthesis of water-adsorbing photocatalysts is exceedingly challenging. In this report, we for the first time present three hygroscopic one-dimensional (1D) covalent organic frameworks (COFs) based on photosensitive pyrene (Py-MPA, Py-PDCA, and Py-HMPA) combined with atmospheric water harvesting (AWH) and photocatalysis for photocatalytic water vapor splitting. Due to the ultra-small pores of the 1D structure, with hydrophilic -OH sites satisfying the microporous filling of water molecules, Py-HMPA demonstrated superior water adsorption capacity at lower humidity. Remarkably, Py-HMPA exhibited an impressive H2 production rate of 105 μmol g−1 h−1 and high stability during solid-state photocatalysis utilizing water vapor. Overall, this work paves a new pathway of organic porous materials for photocatalytic water vapor splitting.

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.

Ethylene elimination can effectively inhibit the rapid aging of fruits and vegetables in storage and transportation. Improving the low-temperature activity, moisture resistance, and stability of Pt based catalysts is a challenge for catalytic oxidation of ethylene which is an effective elimination method. Herein, we constructed ultrasmall MnOx cluster (< 1 nm) on Pt particles via an alloy in situ transformation strategy, which created a large number of MnOx/Pt interfaces. Among all of the samples, 1.89Pt2.20Mn/TiO2 showed the highest catalytic activity in the oxidation of ethylene at a space velocity of 20,000 mL/(g h): T50% = 34 oC and T90% = 43 oC, specific reaction rate at 35 oC = 33.0 µmol/(gPt s), and turnover frequency at 35 oC = 6.5 × 10–3 s−1. In addition, Pt2.20Mn/TiO2 also exhibited better water resistance and stability than Pt/TiO2. The results of XPS, H2O-TPD, C2H4-TPD, in situ DRIFTS, and H218O isotopic tracing characterization revealed that the MnOx/Pt interfacial sites accelerated desorption of CO2 and enhanced the activation of surface active oxygen species (O2 to O22−). Meanwhile, the numerous interfaces provide more active sites for ethylene adsorption and activation, reducing the inhibitory effect of adsorbed water on ethylene adsorption. It was concluded that the prohibited CO2 adsorption, and increased adsorbed oxygen species were responsible for the excellent catalytic performance and good stability of 1.89Pt2.20Mn/TiO2, while the more active sites for ethylene adsorption and activation were responsible for the good water resistance of 1.89Pt2.20Mn/TiO2.

Cu-SSZ-39 zeolites are noted for excellent NH3-SCR activity and hydrothermal stability for applications on diesel vehicles. In this study, Cu-SSZ-39 zeolites were prepared using four precursors. The results showed that the Cu-SSZ-39 prepared using ZSM-5 as precursor (Cu2.5-SSZ-39-Z) has high atomic utilization and the largest particle size, comparing with those using Y, beta and colloidal silica. The Si/Al ratio of Cu2.5-SSZ-39-Z is 9.0, and over 32% of Cu ions are Cu(OH)+ species. Cu2.5-SSZ-39-Z exhibited the best low-temperature NH3-SCR activity and hydrothermal stability. Over 90% of NOx conversion was achieved in the temperature range of 200–550 oC; meanwhile, over 90% NOx conversion could be obtained between 225 oC and 450 oC after hydrothermal aging at 850 oC for 16 h or 900 oC for 5 h. The excellent activity and hydrothermal stability make ZSM-5 the preferred precursor for industrial preparation of Cu-SSZ-39 zeolite.

Photocatalytic reforming of formic acid (FA) is considered a promising energy conversion method for producing solar fuels and valuable chemical feedstocks to achieve the carbon-neutral goal. However, the application of FA photocatalytic reforming has been restricted by the low efficiency and relatively fixed selectivity due to limited knowledge about the reaction mechanism. Herein, we study the efficient CdS/W2N3 photocatalyst system for photoreforming of FA with tunable selectivity to realize the conversion of products from H2 to syngas under simulated sunlight. Widely tunable CO:H2 ratios between 0 and 2.18 along with a record-high apparent quantum yield (AQY) of 61.00% (H2) and 76.84% (syngas) at 420 nm have been demonstrated. Both theoretical investigation and experimental results show that intrinsic N vacancies and spatially separated active sites are vital factors in achieving tunable selectivity. This work provides a insightful information to construct and understand the photocatalytic system for efficiently reforming of FA with tunable selectivity.

Persulfate-based Fenton-like processes are often unsatisfied on the remediation of the complex mediums because the active species of free radicals have usually short lifetime (only 1 µs for hydroxyl radical) or poor selectivity to abatement of the targeted organics. Herein, we report an oxygen-doped carbon catalyst prepared by simple pyrolysis means for persulfate activation to eliminate 2,4-dichlorophenol in the water environment. Experiments and density functional theory calculations uncover reactive sites of the ketonic group displaying the strong site distance effect for the sole active specie of singlet oxygen evolution in the proton-coupled electron transfer regime. Accordingly, the complex water body decontamination has been overwhelmingly realized with the removal efficiency (0.89 (0.007) min−1 for 2,4-dichlorophenol), 3.0–9.4 of pH tolerance, the acceptable stability in continuous-flow and cyclic system. Overall, this work provides novel guidance in metal-free persulfate activation systems for real water remediation.

The effect of ZrO2 crystalline phases on Pd/ZrO2 for catalytic combustion of toluene was investigated. It was found that Pd/t-ZrO2 showed superior activity when the toluene concentration was lower than 2000 ppm, while Pd/m-ZrO2 performed better with toluene concentration higher than 3000 ppm. Kinetic studies showed that the reaction order of toluene on Pd/t-ZrO2 and Pd/m-ZrO2 is 0 and 2, respectively. The catalytic activity was controlled by combined effect of PdO activity and quantity, which was correlated with the interaction between palladium and zirconia. The t-ZrO2 increased PdO species activity, while m-ZrO2 could enhance the amount of PdO. DFT results showed that the p-band center of the O of PdO on t-ZrO2 was higher, suggesting that PdO was more active. In situ-DRIFTS revealed that the reaction pathway of catalytic oxidation of toluene on Pd/ZrO2 was as follows: toluene was oxidized stepwise to benzyl alcohol, benzaldehyde, benzoic acid, CO2 and H2O.

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.

On-site small-scale synthesis of H2O2 using an electrocatalytic reaction with seawater and air as feedstock is crucial for the Fenton reaction to handle marine pollution. However, the reaction is severely constrained by the poisonous effects of excess Cl- in seawater on the 2e- oxygen reduction reaction (ORR) center, necessitating the development of catalysts with high activity and chlorine tolerance. In this study, a catalyst with a high H2O2 yield of 3.33 molg−1h−1 was developed with P-C bond structures whose active center was not only unaffected by Cl- but also promoted the reduction of O2 to H2O2 in the 2e- path when adsorbed Cl- was present. The H2O2 produced in real seawater completely inactivated the algal microorganisms in the flow cell within 10 min. Our results could advance technologies for reducing marine pollution and serve as a guide for the design of catalysts used in Cl--bearing electrolytes.