Physical Blocking Research Articles

Modifying the Substrate-Dependent Pd/Fe2O3 Catalyst-Support Synergism with ZnO Atomic Layer Deposition.

Low-loading Pd supported on Fe2O3 nanoparticles was synthesized. A common nanocatalyst system with previously reported synergistic enhancement of reactivity that is attributed to the electronic interactions between Pd and the Fe2O3 support. Fe2O3-selective precoalescence overcoating with ZnO atomic layer deposition (ALD), using Zn(CH2CH3)2 and H2O as precursors, dampens competitive hydrogenation reactivity at Fe2O3-based sites. The result is enhanced efficiency at the low-loading but high reactivity Pd sites. While this increases catalyst efficiency toward most aqueous redox reactions tested, it suppresses reactivity toward polyaromatic core substrates. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) show minimal electronic impacts for the ZnO overcoat on the Pd particles, implying a predominantly physical site blocking effect as the reason for the modified reactivity. This serves as a proof-of-concept of not only stabilizing supported nanocatalysts but also altering reactivity with ultrathin ALD overcoats. The results point to a facile ALD route for selective enhancement of reactivity for low-loading Pd-based supported nanocatalysts.

Pressure dependence of electrochemical CO2 reduction to ethanol in flow cell

The electroreduction of carbon dioxide (CO2RR) to ethanol is an ideal approach for using released CO2 and producing fuel. The impact of CO2 partial pressure (PCO2) on ethanol synthesis was significant but was not well understood. The present study investigates the pressure dependence of ethanol formation from 0.25 bar to 15 bar in a high-pressure flow cell. It displayed a volcano type. The PCO2 associated with the peak Faradaic efficiency (FE) of ethanol increased as the current density increased. The pressure peak values were 0.5 bar, 0.75 bar at 100, 200, and 300 mA cm−2, respectively. Ethanol formation kinetics was affected by adsorbate-adsorbate interactions and the physical blocking of active sites on catalysts with excess CO2. Besides, ethanol synthesis using the configured flue gas, i.e., low-concentration CO2 (VCO2 = 5–30%), was realized via system pressurization from 5 to 20 bar at 200 mA cm−2. By optimizing the combination of CO2 concentration and total pressure (Ptot), the fuel efficiency (FE) of ethanol was maximized to 26.5%. This study uncovers the ideal CO2 partial pressure for ethanol synthesis under industrial current densities, hence presenting potential industrial applications for utilizing flue gas directly in ethanol production.

Adsorption of sulfamethoxazole and ethofumesate in biochar- and organoclay-amended soil: Changes with adsorbent aging in the laboratory and in the field

Biochars and organoclays have been proposed as efficient adsorbents to reduce the mobility of agrochemicals in soils. However, following their application to soils, these adsorbents undergo changes in their physicochemical properties over time due to their interaction with soil components. In this study, the adsorption capacity of a commercial biochar and a commercial organoclay for the antibiotic sulfamethoxazole (SFMX) and the pesticide ethofumesate (ETFM) was evaluated over aging periods of 3 months in the laboratory and 1 year in the field, subsequent to their application to a Mediterranean soil. The results showed that the adsorption of SFMX and ETFM in the soil amended with the adsorbents was greater than in the unamended soil, but for both chemicals, adsorption decreased with aging of the adsorbents in the soil. Characterization of the adsorbents before and after aging revealed physical blocking of adsorption sites by soil components. The loss of adsorption capacity of the adsorbents upon aging led to higher leaching of SFMX and ETFM in the soil containing field-aged adsorbents, although leaching remained lower than in unamended soil. Our findings reveal that, under the Mediterranean environment studied, the efficacy of the studied materials as adsorbents is maintained to a considerable extent for at least one year after their field application, which would have positive implications in their use for attenuating the dispersion of agricultural contaminants in the environment.

A Natural Casein-Based Separator with Brick-and-Mortar Structure for Stable, High-Rate Proton Batteries.

Rechargeable aqueous proton batteries with small organic molecule anodes are currently considered promising candidates for large-scale energy storage due to their low cost, stable safety, and environmental friendliness. However, the practical application is limited by the poor cycling stability caused by the shuttling of soluble organic molecules between electrodes. Herein, a cell separator is modified by a GO-casein-Cu2+ layer with a brick-and-mortar structure to inhibit the shuttling of small organic molecules. Experimental and calculation results indicate that, attributed to the synergistic effect of physical blocking of casein molecular chains and electrostatic and coordination interactions of Cu2+, bulk dissolution and shuttling of multiple small molecules can be inhibited simultaneously, while H+ transfer across the separators is not almost affected. With the protection of the GO-casein-Cu2+ separator, soluble small molecules, such as diquinoxalino[2,3-a:2',3'-c]phenazine,2,3,8,9,14,15-hexacyano (6CN-DQPZ) exhibit a high reversible capacity of 262.6 mA h g-1 and amazing stability (capacity retention of 92.9% after 1000 cycles at 1 A g-1). In addition, this strategy is also proved available to other active conjugated small molecules, such as indanthrone (IDT), providing a general green sustainable strategy for advancing the use of small organic molecule electrodes in proton cells.

Low temperature soldering technology based on superhydrophobic copper microlayer

Cu–Cu soldering is realized under certain pressure and low temperature conditions by using a surface silver film to modify the copper microlayer structure, thus solving the problems of high thermal stress and signal delay aggravation caused by high temperature in the traditional reflow soldering process. The copper microlayer modified with silver film is obtained by electrodeposition. The surface substructure of the Cu microlayer is a nano cone-shaped protrusion. The diameter of the bottom of the cone is 500 nm∼1 μm, and the height of the cone is 1∼2 μm. The thickness of the silver film is about 320 nm, and the modification of the copper layer with silver film can effectively prevent the oxidation of the copper layer. Two silver-modified copper microlayers are placed in face-to-face contact as a soldering couple. A certain pressure and low temperature are applied to the contact area to realize the soldering and interconnection.The morphology of the soldered interface and the average shear strength of the soldered joints are analyzed by scanning electron microscopy, transmission electron microscopy and solder joint tester. It is found that under the optimal soldering parameters of soldering temperature 220 °C, soldering pressure 20 MPa and soldering time 20 min, the nano-conical projections of the Cu micrometer layer are inserted into each other to produce a physical blocking effect. The highly surface-meltable silver film effectively connects the surrounding copper layer as an intermediate buffer layer. The average shear strength of soldering joints is significantly increased. Heat treatment experiments have shown that the average shear strength can be effectively increased by heat treatment for an appropriate period of time. Prolonged exposure to heat has little effect on the average shear strength. With the special morphology of the copper microlayer structure and the nano-size effect of the silver layer, soldering can be done at low temperatures. The quality of the soldering interface is good and small soldering dimensions can be obtained.

Achieving physical blocking and chemical electrocatalysis of polysulfides by using a separator coating layer in lithium–sulfur batteries

Achieving physical blocking and chemical electrocatalysis of polysulfides by using a separator coating layer in lithium–sulfur batteries

Experimental Water Activity Suppression and Numerical Simulation of Shale Pore Blocking

The nanoscale pores in shale oil and gas are often filled with external nanomaterials to enhance wellbore stability and improve energy production. And there has been considerable research on discrete element blocking models and simulations related to nanoparticles. In this paper, the pressure transmission experimental platform is used to systematically study the influence law of different water activity salt solutions on shale permeability and borehole stability. In addition, the force model of the particles in the pore space is reconstructed to study the blocking law of the particle parameters and fluid physical properties on the shale pore space based on the discrete element hydrodynamic model. However, the migration and sealing patterns of nanomaterials in shale pores are unknown, as are the effects of changes in particle parameters on nanoscale sealing. The results show that: (1) The salt solution adopts a formate system, and the salt solution is most capable of blocking the pressure transmission in the shale pores when the water activity is 0.092. The drilling fluid does not easily penetrate into the shale pore space, and it is more capable of maintaining the stability of the shale wellbore. (2) For the physical blocking numerical simulation, the nanoparticle concentration is the most critical factor affecting the shale pore blocking efficiency. Particle size has a large impact on the blocking efficiency of shale pores. The particle diameter increases by 30% and the pore-blocking efficiency increases by 13% when the maximum particle size is smaller than the pore exit. (3) Particle density has a small effect on the final sealing effect of pore space. The pore-plugging efficiency is only increased by 4% as the particle density is increased by 60%. (4) Fluid viscosity has a significant effect on shale pore plugging. The increase in viscosity at a nanoparticle concentration of 1 wt% significantly improves the sealing effectiveness, specifically, the sealing efficiency of the 5 mPa-s nanoparticle solution is 16% higher than that of the 1 mPa-s nanoparticle solution. Finally, we present a technical basis for the selection of a water-based drilling fluid system for long horizontal shale gas drilling.

Materials Design and System Innovation for Direct and Indirect Seawater Electrolysis.

Green hydrogen production from renewably powered water electrolysis is considered as an ideal approach to decarbonizing the energy and industry sectors. Given the high-cost supply of ultra-high-purity water, as well as the mismatched distribution of water sources and renewable energies, combining seawater electrolysis with coastal solar/offshore wind power is attracting increasing interest for large-scale green hydrogen production. However, various impurities in seawater lead to corrosive and toxic halides, hydroxide precipitation, and physical blocking, which will significantly degrade catalysts, electrodes, and membranes, thus shortening the stable service life of electrolyzers. To accelerate the development of seawater electrolysis, it is crucial to widen the working potential gap between oxygen evolution and chlorine evolution reactions and develop flexible and highly efficient seawater purification technologies. In this review, we comprehensively discuss present challenges, research efforts, and design principles for direct/indirect seawater electrolysis from the aspects of materials engineering and system innovation. Further opportunities in developing efficient and stable catalysts, advanced membranes, and integrated electrolyzers are highlighted for green hydrogen production from both seawater and low-grade water sources.

Zinc hydroxystannate coated by polyphosphazene to improve the fire safety and suppress the smoke of epoxy resin

A novel flame retardant containing zinc, tin, phosphorus and nitrogen elements is synthesized from 4,4-Diaminodiphenyl ether (ODA), Phosphonitrilic chloride trimer (HCCP), Triethylamine (TEA) and 1,4-Dioxane by polycondensation reaction. Herein, a hollow, encapsulated material (hollow zinc hydroxystannate@polyphosphazene, H-ZHS@PZS) is introduced as a flame retardant into epoxy resin (EP). And the hollow structure can delay the release of decomposition products and the diffusion of heat. Thermogravimetric analysis (TGA) shows that the EP has good thermal stability after adding H-ZHS@PZS, and the material weight loss of 5 % corresponds to a minimum temperature of 328.4 °C, and the residual carbon mass increases by 77.7 % compared to the pure EP. The well-designed H-ZHS@PZS has good flame retardancy. Cone calorimeter tests (CCT) show that introducing 5 % H-ZHS@PZS into the EP reduces the peak of heat release rate, total heat release, total smoke production, and peak CO production rate by 55.4 %, 19.7 %, 22.5 %, and 59.3 %, respectively. Benefiting from a well-formed nanosheet-polymer interfaces, the mechanical performance is improved. It is worth noting that the improved flame retardancy of EP is mainly assigned to the physical blocking of H-ZHS and the structure of PZS promotes the formation of a dense and continuous char in the condensed phase.

Soy protein isolate/MXene decorated acidified carbon paper interlayer for long‐cycling Li–S batteries

AbstractThe terrible shuttling of lithium polysulfides (LiPSs) is a major obstacle for commercializing lithium–sulfur (Li–S) batteries as high‐performance energy storage systems. In this study, a carbon‐based interlayer with effective suppression capability on the shuttle effect is developed by simply coating a well‐dispersed mixture of soybean protein isolate/MXene onto the acidified carbon paper (ACP). The resultant composite interlayer (SM@ACP) is able to synergistically diminish the shuttle effect through chemical adsorption and physical blocking. Meanwhile, this interlayer displays excellent conductivity and facilitates the diffusion of Li ions due to the composite coating to promote both electron/ion conduction as well as the porous structure of ACP. Benefiting from the unique properties of the composite interlayer, the as‐assembled Li–S batteries with SM@ACP interlayers show a great improvement in the cycling stability and rate performance, delivering a very low‐capacity decay rate of 0.071% per cycle at 0.5 C even after 800 cycles. This work provides a feasible route to realize rational design and commercial mass production of desirable interlayers for promoting the commercialization of Li–S batteries.

The endowment of monovalent anion selectivity and antifouling property to cross-linked ion-exchange membranes by constructing amphoteric structure

Ion exchange membranes (IEMs) with high monovalent-ion selectivity show promising application in ion resource recovery. In this work, we report a kind of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based on amphoteric ion exchange membranes (AIEMs) having cross-linked structure. Therein, four imidazolium-terminated aliphatic chains (2IM-nC, n = 3, 6, 9, and 12) with varied number of −CH2− were used as crosslinker for cross-linking membrane matrix. Small-angle X-ray scattering tests indicate that the ion cluster sizes of the four AIEMs are evaluated with values of 0.378, 0.384, 0.388 to 0.408 nm, which possibly render the enhanced mono-valent anion selectivity of as-prepared AIEMs. Tested in the electrodialysis (ED) filled with a mixture solution of 0.05 M NaCl + 0.05 M Na2SO4, at current densities of 2.5 mA·cm−2 and 5.0 mA·cm−2, the PSO42-Cl- values of cross-linked AIEM having longer alkyl chains are 20.41 and 22.51, respectively, which are higher than AIEM with shorter cross-linker alkyl chain under the same conditions (3.5). Due to the hydrophilic surface and hydrophilic/negatively charged zwitterionic surface of AIEM, act as useful barriers via physical blocking and electrostatic repulsion, respectively, the anti-fouling performance of IEMs is improved simultaneously. In view of the superior performance, it is believed that the structure–property relationship of AIEM developed here can serve as a guideline for advanced IEMs.

Poisoning of automotive methane oxidation catalysts by silicon compounds

Biomethane production offers a viable option to meet the growing demands of renewable energy sources in the transportation sector. However, biomethane contains trace amounts of impurities, such as siloxanes, that can potentially hinder the methane oxidation catalyst performance and lead to excessive greenhouse gas emissions. To investigate this potential problem, the commercial methane oxidation catalysts were poisoned in a laboratory setup with two common siloxanes found in biomethane and with their combustion product, silica. The performances of the clean and poisoned methane oxidation catalysts were measured under realistic lean-burn conditions, after which the catalyst structural changes were determined using XRD, BET and CO chemisorption. The results revealed two different possible poisoning mechanisms. First, both tested siloxanes poisoned the catalysts by migrating selectively on top of the active metal sites and became combusted to form amorphous silica. This caused the methane oxidation performance to drop rapidly with relatively small amounts of siloxane used. In contrast, a significantly higher dose of silica was required to produce a similar poisoning effect because its poisoning mechanism is based on nonselective deposition and physical blocking of the catalyst surface.

Intraluminal neutrophils limit epithelium damage by reducing pathogen assault on intestinal epithelial cells during Salmonella gut infection.

Recruitment of neutrophils into and across the gut mucosa is a cardinal feature of intestinal inflammation in response to enteric infections. Previous work using the model pathogen Salmonella enterica serovar Typhimurium (S.Tm) established that invasion of intestinal epithelial cells by S.Tm leads to recruitment of neutrophils into the gut lumen, where they can reduce pathogen loads transiently. Notably, a fraction of the pathogen population can survive this defense, re-grow to high density, and continue triggering enteropathy. However, the functions of intraluminal neutrophils in the defense against enteric pathogens and their effects on preventing or aggravating epithelial damage are still not fully understood. Here, we address this question via neutrophil depletion in different mouse models of Salmonella colitis, which differ in their degree of enteropathy. In an antibiotic pretreated mouse model, neutrophil depletion by an anti-Ly6G antibody exacerbated epithelial damage. This could be linked to compromised neutrophil-mediated elimination and reduced physical blocking of the gut-luminal S.Tm population, such that the pathogen density remained high near the epithelial surface throughout the infection. Control infections with a ssaV mutant and gentamycin-mediated elimination of gut-luminal pathogens further supported that neutrophils are protecting the luminal surface of the gut epithelium. Neutrophil depletion in germ-free and gnotobiotic mice hinted that the microbiota can modulate the infection kinetics and ameliorate epithelium-disruptive enteropathy even in the absence of neutrophil-protection. Together, our data indicate that the well-known protective effect of the microbiota is augmented by intraluminal neutrophils. After antibiotic-mediated microbiota disruption, neutrophils are central for maintaining epithelial barrier integrity during acute Salmonella-induced gut inflammation, by limiting the sustained pathogen assault on the epithelium in a critical window of the infection.

Low-Energy Ion Scattering Intensities from Supported Nanoparticles: The Spherical Cap Model

Supported nanoparticles are of great importance to many technologies like fuel processing and chemical synthesis using catalysts and electrocatalysts, energy storage and generation using fuel cells and batteries, electrochemistry, magnetic information storage, and more. Low-energy ion scattering spectroscopy (LEIS) with noble gas ions like He+ is a powerful tool for the characterization of nanoparticles dispersed across flat support surfaces due to its ability to probe the elemental composition in the topmost atomic layer of a surface, providing quantitative information regarding the size and number density of nanoparticles. In this work, we present a derivation of the LEIS intensities expected from nanoparticles and the support material as a function of the average particle size, their number per unit area, and their contact angle with the support when modeled as spherical caps of the nanoparticle material dispersed over the surface of a flat support. The model assumes that the ion intensities are determined only by the physical blocking of linear ion trajectories and independent of the tilt angle of the local surface relative to the incident and scattered ion directions, an assumption we support by quantitative modeling of published data which tested tilt-angle effects. The model is a generalization to arbitrary contact angles of the hemispherical cap model, which assumes 90° contact angle and has been widely used to model spectroscopic signals in LEIS (and also in Auger and photoelectron spectroscopies) during nanoparticle growth. This new model quantitatively reveals how LEIS signals are sensitive not only to the diameter and number density of the nanoparticle but also to their contact angle (or height/diameter ratio). With the use of additional data (e.g., from microscopy or adsorption microcalorimetry), the model presented here will enable more accurate determination of the average size, shape, and number density of supported nanoparticles based on LEIS intensity measurements.

Surface-growing organophosphorus layer on layered double hydroxides enables boosted and durable electrochemical freshwater/seawater oxidation

Developing high-efficiency and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for hydrogen production from electrolysis. Herein, a facile and universal strategy for fabricating organophosphorus (OP) layer encapsulated layered double hydroxide (LDH) is proposed for robust freshwater/seawater oxidation. This approach is based on a self-growing strategy using phytic acid (PA) to realize superb OER activity due to the electron transfer from metal ions in LDH to the phosphate groups in the OP layer. The phosphate group enriched OP layer can also efficiently avoid chloride corrosion via “physical blocking” and “electrostatic repelling”, enabling the OP-NiCo-LDH catalyst to show durable seawater oxidation catalysis performance. It requires an overpotential of 330 mV to deliver a 500 mA cm-2 seawater oxidation with excellent durability for 500 h. Moreover, only 1.59 V is required to achieve a 500 mA cm-2 overall seawater splitting for OP-NiCo-LDH||NiMoN cell. The refore, this work provides a strategy to design robust OER catalysts for industrial water/seawater electrolysis.

Watermelon Flesh-Like Ni3 S2 @C Composite Separator with Polysulfide Shuttle Inhibition for High-Performance Lithium-Sulfur Batteries.

The shuttle effect limits the practical application of lithium-sulfur (Li-S) batteries with high specific capacity and cheap price. Herein, a three-dimensional carbon substrate containing Ni3 S2 nanoparticles is created to modify the separator. The in situ optical visualization battery proves that the material can realize the rapid conversion of Li2 S6 . Moreover, the impact of lithium-ion diffusion on the reactions in the cell is investigated, and the mechanism of Ni3 S2 @C in the cell is proposed based on the "adsorption-diffusion-conversion" mechanism. The "adsorption-diffusion-conversion" process of polysulfide is carried out on the surface of the composite separator, showing positive effects on the inhibition of polysulfide shuttle and the promotion of conversion. The separator is modified to improve sulfur utilization and reduce dead sulfur accumulation through a strategy of chemical immobilization and physical blocking. This helps to bridge the existing gaps of Li-S batteries.

Effect of methyl methacrylate/nitrile rubber/graphene oxide on the anticorrosion and mechanical properties of epoxy‐based coating

AbstractGraphene oxide has a wide application prospect as filler due to its excellent physical blocking, coating reinforcement, and cathodic protection properties. However, graphene oxide is highly susceptible to agglomerative reunions. Three types of anti‐corrosion coatings were prepared on 5083 Al alloy by a simple smearing method. The coatings are based on neat epoxy resin by introducing different amounts of graphene oxide, methyl methacrylate/nitrile rubber, and methyl methacrylate/nitrile rubber/ graphene oxide fillers. Thermogravimetric analysis (TGA) results show that methyl methacrylate/nitrile rubber/graphene oxide fillers enhance the thermal stability of the epoxy resin‐based coatings. The SEM morphology shows the well‐dispersed methyl methacrylate/nitrile rubber/graphene oxide in the coating. The 2 and 1 wt% methyl methacrylate/nitrile rubber/graphene oxide coating exhibits excellent mechanical properties and outstanding anti‐corrosion properties, respectively. At 1 wt%, the OCP of the coating is −0.21 V. Additionally, the coating exhibits great anti‐corrosion performance after immersion for 196 h. Compared to the pristine coating and methyl methacrylate/nitrile rubber coatings, the methyl methacrylate/nitrile rubber/graphene oxide coatings show better thermal stability, mechanical properties and anti‐corrosion properties. The methyl methacrylate/nitrile rubber fillers degrade the thermal stability and anti‐corrosion protection and do not affect mechanical properties. Compared with graphene oxide coatings, the surface of methyl methacrylate/nitrile rubber/graphene oxide coatings is smoother with better dispersion, possessing better mechanical and anti‐corrosion properties though only a fewer amounts of graphene oxide were filled in epoxy resin. The better corrosion resistance of the coating can be attributed to the synergistic effect of a physical barrier and a coulomb block.

Numerical Simulation Study on Spatial Diffusion Behavior of Non-Point Source Fugitive Dust under Different Enclosure Heights

Non-point source fugitive dust produced during municipal road construction is one of the main ambient air pollutants gravely threatening the life and health of construction workers and residents around construction areas. In this study, a gas-solid two-phase flow model is used to simulate the diffusion behavior of non-point source dust with different enclosure heights under wind loads. Moreover, the inhibitory effect of the enclosure on the diffusion of non-point source dust from construction to residential areas is analyzed. The results show that the physical blocking and reflux effects of the enclosure can effectively restrain dust diffusion. When the enclosure height is 3-3.5 m, the concentration of particulate matter in most sections of residential areas can be reduced to less than 40 μg/m3. Moreover, when the wind speed is 1-5 m/s and the enclosure height is 2-3.5 m, the diffusion height of non-point source dust particles above the enclosure is concentrated in the range 1.5-2 m. This study provides a scientific basis for setting the heights of enclosures and atomization sprinklers at construction sites. Further, effective measures are proposed to reduce the impact of non-point source dust on the air environment of residential areas and health of residents.

Hierarchical lamellar single-walled carbon nanotube aerogel interlayers for stable lithium-sulfur batteries with high-sulfur-loading

Lithium-sulfur (Li-S) battery has been recognized as a new energy storage device with broad prospects because of its satisfactory specific capacity and theoretical energy density. Nevertheless, the shuttle effect of polysulfides seriously hinders the real applications of high-sulfur-loaded Li-S batteries. To remove the hurdle, hierarchical lamellar single-walled carbon nanotube aerogels (SWCNTAs) are herein fabricated and applied as multifunctional interlayers in Li-S batteries, which exhibit an initial area-specific capacity as high as 7.1 mAh cm−2 at a sulfur loading of 8.02 mg cm−2. The introduced SWCNTA interlayers can lower the internal resistance and suppress the shuttling of polysulfides by a layer-by-layer physical blocking mechanism. Moreover, owing to the super wettability of SWCNTAs, electrolytes with a dosage of 10 μL mg−1 could effectively wet and infiltrate the interlayers, rendering the lean-electrolyte Li-S batteries a high specific capacity of 559 mAh g−1 at a sulfur loading of 10.35 mg cm−2 after 60 cycles. This work presents an example for rationally designing the interlayers structures for high-sulfur loading batteries, which paves a stepping stone for the future commercialization of Li-S batteries.

Revealing key factors influencing enzymatic digestibility of hydrothermally pretreated poplar in comparison with corn stover

Poor enzymatic digestibility of pretreated biomass is recognized as the main technical hindrance toward the biorefining of hardwood, beginning with hydrothermal pretreatment. The key factors influencing enzymatic digestibility of hydrothermally pretreated poplar (HP-PS) were investigated with hydrothermally pretreated corn stover (HP-CS) as comparisons in this study. Results showed a low glucose yield was observed for HP-PS (23.7%) in comparison with HP-CS (63.0%). The effects of lignin content, lignin inhibition mechanism, and lignin distribution on the enzymatic digestibility of HP-PS and HP-CS were compared. It suggested that the high content of lignin, which was in relatively homogenous distribution, mainly affected the bioconversion of HP-PS by impeding cellulase via physical blockage. Additionally, correlations among other factors and glucose yields were also analyzed, revealing the key inhibitory effect of surface lignin content on the bioconversion efficiency of HP-PS. The enzymatic digestibility of poplar was improved to 84.6% as a result of the disruption of lignin-derived physical blocking. These results give insights into developing strategies for the efficient bioconversion of hardwood candidates for biorefinery feedstocks.