An energy-efficient solution to sludge drying and combustion process through Camellia oleifera shells amended foaming.

Foaming pretreatment has been proven effective in promoting sludge drying, however, the variation in sludge properties significantly influences the foaming efficiency. Inspired by foam stabilizer of solid particles, Camellia oleifera shells (COS) was screened out from various biomasses as an additive incorporated with the CaO for promoting the sludge foaming. For the introduction of COS, this study analyzed the drying behaviors of foamed sludge, quantified the surface cracks information, characterized the combustion performance, and evaluated the energy consumption. The results indicated that 46.72-50.10% of time could be saved in foaming the sludge to 0.70 g/mL by addition of 3.0 wt% COS. Compared with the original sludge (OS), the 0.70 g/mL foamed sludge saved 47.43% of time for sludge drying at 80 °C, and this value further increased to 53.14% with 3.0 wt% COS addition. Combining the multifractal spectra and drying kinetics analysis, the foaming promoted the formation of complex surface cracks in the warm-up period, while COS further improved the complexity of cracks in the constant rate period, and the shrinkage of isolated sludge blocks in the falling rate period, thus enhanced the moisture diffusion and heat transfer. Furthermore, the appropriate porous structure and additional volatile matters promoted the combustion performance. The 0.90 g/mL foamed sludge with COS presented the lowest activation energy of 180.362 kJ/mol in combustion. Overall, compared with OS, the 0.70 g/mL foamed sludge with COS saved 40.65% energy consumption during the foaming, drying and combustion processes, providing an energy-efficient solution for the sludge treatment and disposal.

Implanting oxophilic metal in PtRu nanowires for hydrogen oxidation catalysis.

Bimetallic PtRu are promising electrocatalysts for hydrogen oxidation reaction in anion exchange membrane fuel cell, where the activity and stability are still unsatisfying. Here, PtRu nanowires were implanted with a series of oxophilic metal atoms (named as i-M-PR), significantly enhancing alkaline hydrogen oxidation reaction (HOR) activity and stability. With the dual doping of In and Zn atoms, the i-ZnIn-PR/C shows mass activity of 10.2 A mgPt+Ru-1 at 50 mV, largely surpassing that of commercial Pt/C (0.27 A mgPt-1) and PtRu/C (1.24 A mgPt+Ru-1). More importantly, the peak power density and specific power density are as high as 1.84 W cm-2 and 18.4 W mgPt+Ru-1 with a low loading (0.1 mg cm-2) anion exchange membrane fuel cell. Advanced experimental characterizations and theoretical calculations collectively suggest that dual doping with In and Zn atoms optimizes the binding strengths of intermediates and promotes CO oxidation, enhancing the HOR performances. This work deepens the understanding of developing novel alloy catalysts, which will attract immediate interest in materials, chemistry, energy and beyond.

The synergistic regulation of sewage sludge biodrying and greenhouse gas reduction by additives.

As a dewatering method of high moisture solid waste sludge, biodrying still faces environmental problems such as material loss and greenhouse gas emission in the process of treatment. In this study, biochar and magnesium chloride were used to explore the synergistic effect of enhancing sludge biodrying and reducing greenhouse gas emissions. The highest temperature of biodrying was raised to 68.2 °C within 3 days, extending the longest high-temperature period to 5 days, which reduced the water content to 28.8 % in the single addition of biochar treatment. The complex addition increased the NH4+-N content of materials by 57.49 % and decreased the NO3--N content of materials by 40.62 %. The use of additives significantly reduced the emissions of CO2, CH4, and N2O compared to the no-addition treatment. The increase in dominant Actinomycetes and Chloroflexibacter was the main reason for the reduction in gas emissions.

Functional keystone taxa promote N and P removal of the constructed wetland to mitigate agricultural nonpoint source pollution.

Characterized by irregular spatial and temporal variations of pollutant loading and complex occurrence mechanisms, agricultural nonpoint source pollution (ANPSP) has always been a great challenge in field restoration worldwide. Returning farmlands to wetlands (RFWs) as an ecological restoration mode among various constructed wetlands was selected to manage ANPSP in this study. Triarrhena lutarioriparia, Nelumbo nucifera and Zizania latifolia monocultures were designed and the water pollutants was monitored. N. nucifera and Z. latifolia could reach the highest TN (53.28 %) and TP (53.22 %) removal efficiency, respectively. By 16s high-throughput sequencing of rhizosphere bacteria, 45 functional species were the main contributors for efficient N and P removal, and 38 functional keystone taxa (FKT) were found with significant ecological niche roles and metabolic functions. To our knowledge, this is the first study to explore the microbial driving N and P removal mechanism in response to ANPSP treated by field scale RFWs.

Endophytic Enterobacter sp. YG-14 mediated arsenic mobilization through siderophore and its role in enhancing phytostabilization.

Soil arsenic (As) phytoremediation has long faced the challenge of efficiently absorbing As by plant accumulators while maintaining their health and fast growth. Even at low doses, arsenic is highly toxic to plants. Therefore, plant growth-promoting microorganisms that can mediate As accumulation in plants are of great interest. In this study, the endophyte Enterobacter sp. YG-14 (YG-14) was found to have soil mobilization activity. By constructing a siderophore synthesis gene deletion mutant (ΔentD) of YG-14, the endophyte was confirmed to effectively mobilize Fe-As complexes in mining soil by secreting enterobactin, releasing bioavailable Fe and As to the rhizosphere. YG-14 also enhances As accumulation in host plants via extracellular polymer adsorption and specific phosphatase transfer protein (PitA) absorption. The root accumulation of As was positively correlated with YG-14 root colonization. In addition, YG-14 promoted plant growth and alleviated oxidative damage in R. pseudoacacia L. under arsenic stress. This is the first study, from phenotype, physiology, and molecular perspectives, to determine the role of endophyte in promoting As phytostabilization and maintaining the growth of the host plant. This demonstrated the feasibility of using endophytes with high siderophore production to assist host plants in As phytoremediation.

Seed rain composition responds to climate change in a subtropical forest.

Recent climate change has been shown to alter aspects of forest plant demography, such as growth and mortality, but less attention has been focused on how climate change alters the reproduction of plant populations through time. We hypothesized that the plant seed production would respond to climate change, and that the response would differ according to plant life form and functional traits. We tested this hypothesis by examining climate change from 2005 to 2020 and by determining the temporal trends of seed rain and seed production from plants with different life forms (e.g., herbs, vines, trees, palms) and of tree species with different statures as well as leaf, seed and wood traits during 2014-2020. We also tested the correlation between meteorological variables and time series of seed rain using cross correlation analysis. We found increasing wetness (lower vapor pressure deficit) through time but with decreasing minimum relative humidity, which is a pattern consistent with trends seen in many other parts of the world. During the study period, seed production of shrubs and relative contribution of woody vines to total seed rain decreased, while relative contribution of palms to total seed rain and tree species with more conservative leaf traits increased their contribution to total seed rain. Overall, these trends were well explained by the trends of meteorological variables and the responses of these life forms to climate change in previous studies. Additionally, the increasingly conservative leaf traits were also consistent with shifts in traits following recovery from disturbance. Our results suggest that a trait-based approach may help to unveil trends that are not readily apparent by examining seed counts alone. The compositional change found in the seed rain may indicate future shifts in forest species composition and should be incorporated into future studies of forest modelling and projections under climate change.

Metal-Organic Framework Derived Cu-Ag Interface for Selective Carbon Monoxide Electroreduction to Acetate.

Electrochemical carbon monoxide reduction reaction (CORR) is a potential way to obtain high-value multi-carbon (C2+ ) products. However, achieving high selectivity to acetate is still a challenge. Herein, we develop a two-dimensional Ag-modified Cu metal-organic framework (Ag0.10 @CuMOF-74) that demonstrates Faradaic efficiency (FE) for C2+ products up to 90.4 % at 200 mA cm-2 and an acetate FE of 61.1 % with a partial current density of 122.2 mA cm-2 . Detailed investigations show that the introduction of Ag on CuMOF-74 favors the generation of abundant Cu-Ag interface sites. In situ attenuated total reflection surface enhanced infrared absorption spectroscopy confirms that these Cu-Ag interface sites improve the coverage of *CO and *CHO and the coupling between each other and stabilize key intermediates *OCCHO and *OCCH2 , thus significantly promoting to the acetate selectivity on Ag0.10 @CuMOF-74. This work provides a high-efficiency pathway for CORR to C2+ products.

Interfacial Synergy between the Cu Atomic Layer and CeO2 Promotes CO Electrocoupling to Acetate.

Cu is considered to be an effective electrocatalyst in CO/CO2 reduction reactions (CORR/CO2RR) because of its C-C coupling into C2+ products, but it still remains a formidable challenge to rationally design Cu-based catalysts for highly selective CO/CO2 reduction to C2+ liquid products such as acetate. We here demonstrate that spraying atomically layered Cu atoms onto CeO2 nanorods (Cu-CeO2) can lead to a catalyst with an enhanced acetate selectivity in CORR. Owing to the existence of oxygen vacancies (Ov) in CeO2, the layer of Cu atoms at interface coordinates with Ce atoms in the form of Cu-Ce (Ov), as a result of strong interfacial synergy. The Cu-Ce (Ov) significantly promotes the adsorption and dissociation of H2O, which further couples with CO to selectively produce acetate as the dominant liquid product. In the current density range of 50-150 mA cm-2, the Faradaic efficiencies (FEs) of acetate are over 50% with a maximum value of 62.4%. In particular, the turnover frequency of Cu-CeO2 reaches 1477 h-1, surpassing that of Cu nanoparticle-decorated CeO2 nanorods, bare CeO2 nanorods, as well as other existing Cu-based catalysts. This work advances the rational design of high-performance catalysts for CORR to highly value-added products, which may attract great interests in diverse fields including materials science, chemistry, and catalysis.

Magnetic biochar promotes the risk of mobile genetic elements propagation in sludge anaerobic digestion.

Mobile genetic elements (MGEs) mediated horizontal gene transfer is the primary reason for the propagation of antibiotic resistance genes in environment. The behavior of MGEs under magnetic biochar pressure in sludge anaerobic digestion (AD) is still unknown. This study evaluated the effects of different dosage magnetic biochar on the MGEs in AD reactors. The results showed that the biogas yield was highest (106.68 ± 1.16 mL g-1 VSadded) with adding optimal dosage of magnetic biochar (25 mg g-1 TSadded), due to it increased the microorganism's abundance involved in hydrolysis and methanogenesis. While, the total absolute abundance of MGEs in the reactors with magnetic biochar addition increased by 11.58%-77.37% compared with the blank reactor. When the dosage of magnetic biochar was 12.5 mg g-1 TSadded, the relative abundance of most MGEs was the highest. The enrichment effect on ISCR1 was the most significant, and the enrichment rate reached 158.90-214.16%. Only the intI1 abundance was reduced and the removal rates yield 14.38-40.00%, which was inversely proportional to the dosage of magnetic biochar. Co-occurrence network explored that Proteobacteria (35.64%), Firmicutes (19.80%) and Actinobacteriota (15.84%) were the main potential host of MGEs. Magnetic biochar changed MGEs abundance by affecting the potential MGEs-host community structure and abundance. Redundancy analysis and variation partitioning analysis showed that the combined effect of polysaccharides, protein and sCOD exhibited the greatest contribution (accounted for 34.08%) on MGEs variation. These findings demonstrated that magnetic biochar increases the risk of MGEs proliferation in AD system.

Effects of Magnetic Biochar Addition on Mesophilic Anaerobic Digestion of Sewage Sludge.

As a low-cost additive to anaerobic digestion (AD), magnetic biochar (MBC) can act as an electron conductor to promote electron transfer to enhance biogas production performance in the AD process of sewage sludge and has thus attracted much attention in research and industrial applications. In the present work, Camellia oleifera shell (COS) was used to produce MBC as an additive for mesophilic AD of sewage sludge, in order to explore the effect of MBC on the mesophilic AD process and its enhancement mechanism. Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectrometry (FTIR), and X-ray diffraction (XRD) further confirmed that biochar was successfully magnetized. The yield of biogas from sewage sludge was enhanced by 14.68-39.24% with the addition of MBC, and the removal efficiency of total solid (TS), volatile solids (VS), and soluble chemical oxygen demand (sCOD) were 28.99-46.13%, 32.22-48.62%, and 84.18-86.71%, respectively. According to the Modified Gompertz Model and Cone Model, the optimum dosage of MBC was 20 mg/g TS. The maximum methane production rate (Rm) was 15.58% higher than that of the control reactor, while the lag-phase (λ) was 43.78% shorter than the control group. The concentration of soluble Fe2+ and Fe3+ were also detected in this study to analyze the function of MBC for improving biogas production performance from sewage sludge. The biogas production was increased when soluble Fe3+ was reduced to soluble Fe2+. Overall, the MBC was beneficial to the resource utilization of COS and showed a good prospect for improving mesophilic AD performance.

Effects of initial particle sizes of Triarrhena lutarioriparia on processing performance, material properties, and heavy metal speciation in sewage sludge composting.

The purpose of this study was to investigate the effect of initial particle size (IPS) on the environmental parameters and heavy metal speciation during sludge composting. Three piles were conducted: fine material (FM, screen underflow), coarse material (CM, oversize product), and mixed material (MM, mix FM and CM in 1:1). Results showed that the temperature trends of the three piles in different layers were highly repeatable during the thermophilic period. With the decrease of IPS, the heating rate and the highest temperature of the pile increased, the thermophilic period was prolonged, and the highest temperature area in the pile shifted to a lower layer. It also promoted the organic matter degradation, compost maturation, and nitrogen fixation effect. Composting had a good effect on the passivation of heavy metals, especially Cd, Cu, and Pb. The passivation effect on Cd and Cu was FM > CM > MM, and on Pb was CM > FM > MM. Fourier transform infrared spectroscopy, excitation-emission matrix, and thermogravimetric thermal analysis indicated that FM had the highest content of aromatic structure and humic-like substance on D40. The redundancy analysis revealed that MM was beneficial to improve the internal uniformity during composting.

Synthesis of Porous Hollow Spheres Co@TiO2-x-Carbon Composites for Highly Efficient Lithium-Ion Batteries.

The hollow TiO2 anode material has received great attention for next-generation LIBs because of its excellent stability, environmental friendly, and low volume change during lithiation/delithiation. However, there are some problems associated with the current anatase TiO2 anode materials in practical application owing to low lithium-ion diffusivity and poor reversible theoretical capacities. The introduction of defects has been turned out to be a significant and effective method to improve electronic conductivity, especially oxygen vacancies. In this paper, a facile hydrothermal reaction and subsequent chemical vapor deposition method were successfully used to fabricate Co@TiO2-x-carbon hollow nanospheres. These results suggest that the synthesized product exhibits good rate performance and superior cycling stability.

A field study on the composition, structure, and function of endophytic bacterial community of Robinia pseudoacacia at a composite heavy metals tailing.

Robinia pseudoacacia (R. pseudoacacia) is a well reported plant species for heavy metal phytoremediation, and it was capable to improve Cd uptake efficiency after inoculated with plant growth promoting endophytes. However, the knowledge on R. pseudoacacia associated endophytes in field condition and the relationship between these microbial communities and heavy metal uptake capacities are still scarce. In this study, the characteristics of heavy metal bioaccumulation and translocation in R. pseudoacacia, and the structure and function of its endophytic bacterial communities were revealed. The results showed that heavy metal pollution made microbes more sensitive to the environment as the diversity (Shannon) of endophyte community decreased but the abundance (Chao) increased. Redundancy analysis (RDA) also showed that heavy metals were the key factor affecting the composition of endophyte. In the co-occurrence network, 27 keystone taxa mainly from Actinobacteria, Proteobacteria and Firmicutes occupied the dominant niches, among which 16 OTUs mainly from lactobacillus, bacteroides, staphylococcus, methylorubrum and bifidobacterium were positively related to bioaccumulation and translocation of Cd, Cu, Pb and Zn. Besides, heavy metal stress enhanced the functional adaptability of endophytic bacteria community. Related predicted genes were enriched in immune response, physiological metabolism pathway and stress-resistant enzyme synthesis. This study showed that heavy metal stress enhanced the structural and functional adaptability of endophyte community and keystone taxa played significant role in improving the efficiency of phytoremediation.

Spatial-Temporal Evolution and Driving Forces of NDVI in China's Giant Panda National Park.

Identifying the ecological evolution trends and vegetation driving mechanisms of giant panda national parks can help to improve the protection of giant panda habitats. Based on the research background of different geomorphological zoning, we selected the MODIS NDVI data from 2000 to 2020 to analyze the NDVI trends using a univariate linear model. A partial correlation analysis and multiple correlation analysis were used to reveal the influence of temperature and precipitation on NDVI trends. Fourteen factors related to meteorological factors, topographic factors, geological activities, and human activities were selected, and the Geographically Weighted Regression model was used to study the mechanisms driving NDVI change. The results were as follows: (1) The NDVI value of Giant Panda National Park has fluctuated and increased in the past 21 years, with an annual growth rate of 4.7%/yr. Affected by the Wenchuan earthquake in 2008, the NDVI value fluctuated greatly from 2008 to 2012, and reached its peak in 2018. (2) The NDVI in 94% of the study area improved, and the most significant improvement areas were mainly distributed in the northern and southern regions of Southwest Subalpine and Middle Mountain and the Xiaoxiangling area. Affected by the distribution of fault zones and their local activities, vegetation degradation was concentrated in the Dujiangyan-Anzhou area of Hengduan Mountain Alpine Canyon. (3) The Geographically Weighted Regression analysis showed that natural factors were dominant, with climate and elevation having a double-factor enhancement effect, the peak acceleration of ground motion and fault zone having a superimposed effect, and river density and slope having a double effect, all of which had a significant impact on the NDVI value of the surrounding area. To optimize the ecological security pattern of the Giant Panda National Park, we recommended strengthening the construction of ecological security projects through monitoring meteorological changes, preventing, and controlling geo-hazards, and optimizing the layout and intensity of human activities.

Effect of Anoxic Atmosphere on the Physicochemical and Pelletization Properties of Pinus massoniana Sawdust during Storage.

The 34-day anoxic storage of Pinus massoniana sawdust (PS) in a sealed constant temperature and humidity chambers was carried out to simulate the limited-oxygen storage process inside piles at industrial scale. The effects of anoxic storage on feedstock's properties and pelletization process were investigated with respect to elemental composition, dry matter loss, thermogravimetric characteristics, energy consumption, pellets' density, and microbial communities, etc. After anoxic storage, the microbial community of PS samples was altered, such as the fungi content (Clonostachys, Strelitziana, and Orbilia, etc.), resulting the elemental composition of PS was altered. Thus, the cellulose and ash content of the stored PS were increased, while the hemicellulose, volatile, and fixed carbon were decreased. The energy consumption was increased 7.85-21.98% with the increase in anoxic storage temperature and with the additive of fresh soil collected from PS field in storage process. The single pellet density was altered slightly. Meanwhile, the moisture uptake of PS pellets was decreased. After anoxic storage, the combustion behavior of the stored PS became more stable. The results can be applied directly to guide the development of commercial PS storage and pelletization process currently under development in Asia, Europe and North America.

Enhanced Cd phytostabilization and rhizosphere bacterial diversity of Robinia pseudoacacia L. by endophyte Enterobacter sp. YG-14 combined with sludge biochar.

Robinia pseudoacacia L., a pioneer woody legume grown in mining areas, has been recognized as a remarkable accumulator of various heavy metals. Compared with other hazardous heavy metals (HMs), it is of low capacity in accumulating Cd, which, as a result, may hinder the phytoremediation efficiency. To enhance R. pseudoacacia's uptake efficiency of Cd, the individual effects of various rhizobia and arbuscular mycorrhizal fungi have been reported, however, the combined influence of endophytes and biochar receives little attention. In the current study, a Cd-adsorbing endophyte Enterobacter sp. YG-14 was inoculated to R. pseudoacacia, and its extraordinary effect on increasing R. pseudoacacia's Cd uptake was found, which was ascribed to the reinforced root Cd chelation by the strain through secreting siderophores/LMWOAs. Further, P-enriched sludge biochar was applied along with YG-14 to form a combined biochar-endophyte-accumulator system, in which biomineralization were reinforced (i.e. CdCO3 and Cd2P2O7 were generated), as the total and acid-soluble Cd in rhizosphere were reduced by 61.75% and 69.01% respectively, and soil's bacterial diversity was further improved with diversified N2-fixing microbial biomarkers. Multiple synergistic effects (E > 0) were also found, with the optimum performance on plant growth parameters (increased by 39.61%-561.91%) in comparison to the control group. Moreover, the system exhibited a preferable Cd phytostabilization capacity with the highest increase (81.42%) in Cd accumulation and a significant reduction (72.73%) in Cd root-to-shoot translocation.

Long-term effects of phytoextraction by a poplar clone on the concentration, fractionation, and transportation of heavy metals in mine tailings.

Mine tailings are one of main causes of diffused heavy metal pollution since the heavy metals in there may acquire mobility. The current knowledge of the processes at work in long-term phytoremediation by woody species remains insufficient. Through a 4-year field study, we evaluated the phytoextraction efficiency of Populus deltoides CL. 'Xianglin 90' grown on a mine tailing co-polluted by Cd, Cu, Cr, Ni, Pb, and Zn. The concentrations of Cd, Cu, Ni, Pb, and Zn in the rhizospheric soil were reduced by amounts ranging from 12.86 to 42.19% during the study period. Bioconcentration factors and translocation factors showed that the accumulation of Cd and Zn occurring in the shoots was the most effective. Combined with the considerable biomass produced by poplar, the extracted amounts of Cd and Zn could reach 0.61 g and 10.66 g plant-1, respectively, in which the shoots account for 77.3% (Cd) and 89.0% (Zn) of the overall extraction amounts. Acid-soluble Cd and Zn increased by 5.49% and 4.29%, respectively, in the rhizosphere compared to the bulk soil, indicating that poplar enhanced the mobility of Cd and Zn in the rhizosphere, which explained its ability for bioaccumulation and root-shoot translocation. Moreover, calculated time required to address the issue of Cd and Zn pollution was theoretically shortened by more than half from 2015 to 2019. This study brings new insights into the long-term effects of phytoextraction on the concentration, fractionation, and transportation of heavy metals and confirms the potential of poplar as a Cd and Zn remediation species.

Improving light absorption and photoelectrochemical performance of thin-film photoelectrode with a reflective substrate.

The charge separation/transport efficiency is relatively high in thin-film hematite photoanodes in which the distance for charge transport is short, but simultaneously the high loss of light absorption due to transmission is confronted. To increase light absorption in thin-film Fe2O3:Ti, commercial substrates such as Cu foil, Ag foil, and a mirror are adopted acting as back-reflectors and individually integrated with the Fe2O3:Ti electrode. The promotion effect of the commercial back-reflectors on the light absorption efficiency and photoelectrochemical (PEC) performance of the hydrothermally prepared Fe2O3:Ti electrodes with a variety of film thicknesses is investigated. As a result, Ag foil and the mirror show favorable and equal efficacy while the promoting effect of Cu foil is limited. In addition, the photocurrent increment achieved by the Ag back-reflector decreases linearly along with the logarithmic of the film thickness and the optimized film thickness of the Fe2O3:Ti electrode is decreased from 520 to 290 nm. The high durability of Ag foil in the alkaline electrolyte during solar light irradiation is demonstrated. Furthermore, the reflective substrate also shows a promotion effect on the BiVO4 photoanode and CuBi2O4 photocathode, as well as the unbiased photocurrent from a tandem cell constituted by TiO2 and CuBi2O4.

Metal oxide/CeO2 nanocomposites derived from Ce-benzene tricarboxylate (Ce-BTC) adsorbing with metal acetylacetonate complexes for catalytic oxidation of carbon monoxide.

Herein, a series of metal oxide/CeO2 (M/CeO2) nanocomposites derived from Ce-benzene tricarboxylate (Ce-BTC) adsorbing with different metal acetylacetonate complexes were prepared for CO oxidation under four different CO gas atmospheres. It was demonstrated that Cu/CeO2 exhibited the highest catalytic activity and stability in CO oxidation. Remarkably, both O2 selectivity and CO selectivity to CO2 are 100% in most of the investigated conditions. Several analytical tools such as N2 adsorption-desorption and powder X-ray diffraction, were employed to characterize the prepared catalysts. In addition, the excellent catalytic performance of Cu/CeO2 in CO oxidation was revealed by H2 temperature-program reduction experiment, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The result showed that high oxygen vacancy and high CO adsorption capacity (Cu+-CO) caused by the electron exchanges of Cu2+/Cu+ and Ce3+/Ce4+ pairs (Ce4+ + Cu+ ⇆ Ce3+ + Cu2+) are two key factors contributing to the high oxidation performance of Cu/CeO2 catalyst.

Biomimetic Au/CeO2 Catalysts Decorated with Hemin or Ferrous Phthalocyanine for Improved CO Oxidation via Local Synergistic Effects.

Biomimetic catalysts have drawn broad research interest owing to both high specificity and excellent catalytic activity. Herein, we report a series of biomimetic catalysts by the integration of biomolecules (hemin or ferrous phthalocyanine) onto well-defined Au/CeO2, which leads to the high-performance CO oxidation catalysts. Strong electronic interactions among the biomolecule, Au, and CeO2 were confirmed, and the CO uptake over hemin-Au/CeO2 was roughly about 8 times greater than Au/CeO2. Based on the Au/CeO2(111) and hemin-Au/CeO2(111) models, the density functional theory calculations reveal the mechanisms of the biomolecules-assisted catalysis process. The theoretical prediction suggests that CO and O2 molecules preferentially bind to the surface of noncontacting Au atoms (low-coordinated sites) rather than the biomolecule sites, and the accelerating oxidation of Au-bound CO occurs via either the Langmuir-Hinshelwood mechanism or the Mars-van Krevelen mechanism. Accordingly, the findings provide useful insights into developing biomimetic catalysts with low cost and high activity.