Structure-performance Relationship Research Articles

Zinc‐Ion Battery Chemistries Enabled by Regulating Electrolyte Solvation Structure

AbstractDesigning next‐generation alternative energy storage devices that feature high safety, low cost, and long operation lifespan is of the utmost importance for future wide range of applications. Aqueous zinc‐ion batteries play a vital part in promoting the development of portability, sustainability, and diversification of rechargeable battery systems. Based on the theory of electrolyte solvation chemistry, deep understanding of interaction between electrolyte components and their impact on the chemical properties has achieved a series of research progress. Analyzing the solvation shell of electrolyte or structure–performance relationship, and establishing more stable and high‐energy battery chemistries are inevitable requirements to suppress the electrolyte–electrode interphase side reaction and realize the functional use of zinc‐ion batteries. In this critical review, the attempt is to overview the current comprehension regarding the electrolyte solvation structure in zinc battery technology. Advanced methodology toward the interactions between zinc cations, solvent molecules, and anions in zinc aqueous electrolytes and the general rules for electrolyte design from the atomic level are summarized. Methods for viable solvation modification are then introduced regarding overcoming the remained challenges for transferring the laboratory results to next‐generation practical applications. Possible research direction with the aim of investigating the ultimate choice for future high‐performance electrolyte solvation construction is also outlined.

Toward better halon substitutes: Effects of carbon chain length on pyrolytic and fire-suppressing mechanisms of perfluoroalkanes

The use of halon fire extinguishants has led to the depletion of the ozone layer, prompting numerous international organizations to invest significant efforts in finding suitable halon alternatives. Among the counterparts, perfluorinated compounds stand out due to their environmental friendliness, specifically, CF3CF3, CF3CF2CF3 and CF3CF2CF2CF3 have been identified by NASA as the most promising candidates within this chemical family. This study digs into the impact of carbon chain length on thermal decomposition and fire suppression mechanisms of perfluoroalkanes with the three agents as model substances, employing experimental and theoretical analyses. Thermal decomposition products within the temperature range of 600 °C - 900 °C and fire suppression performances, including fire-extinguishing concentrations (9.38 vol.%, 7.81 vol.%, and 6.87 vol.%, respectively), variation of the flame morphology and temperature, are intensively analyzed and compared for the three perfluoroalkanes. Theoretical calculations indicate a decrease in carbon chain stability with the increasing chain length, and CF3CF2CF2CF3 manifests the most diversified self-decomposition paths at low energy barriers. Moreover, a wider spectrum of free radicals can be generated from the longer carbon chain via the CC cleavage, which can efficiently react with and continuously consume flame radicals (H• and OH•) to interrupt the combustion chain reaction. These findings enrich the structure-performance relationship of perfluoroalkanes, highlight the potential of specific perfluorinated compounds as viable halon alternatives and offer theoretical guidance for the selection and design of environmentally benign and efficient halon substitutes.

Multilaminate Energy Storage Films from Entropy-Driven Self-Assembled Supramolecular Nanocomposites.

Composite materials comprising polymers and inorganic nanoparticles (NPs) are promising for energy storage applications, though challenges in controlling NP dispersion often result in performance bottlenecks. Realizing nanocomposites with controlled NP locations and distributions within polymer microdomains is highly desirable for improving energy storage capabilities but is a persistent challenge, impeding the in-depth understanding of the structure-performance relationship. In this study, a facile entropy-driven self-assembly approach is employed to fabricate block copolymer-based supramolecular nanocomposite films with highly ordered lamellar structures, which are then used in electrostatic film capacitors. The oriented interfacial barriers and well-distributed inorganic NPs within the self-assembled multilaminate nanocomposites effectively suppress leakage current and mitigate the risk of breakdown, showing superior dielectric strength compared to their disordered counterparts. Consequently, the lamellar nanocomposite films with optimized composition exhibit high energy efficiency (>90% at 650MVm-1), along with remarkable energy density and power density. Moreover, finite element simulations and statistical modeling have provided theoretical insights into the impact of the lamellar structure on electrical conduction, electric field distribution, and electrical tree propagation. This work marks a significant advancement in the design of organic-inorganic hybrids for energy storage, establishing a well-defined correlation between microstructure and performance.

Nature of C-C coupling and strategy of tuning the catalytic activity of Cu-N-C catalysts for electro-reduction of CO2 to ethanol

With high atomic utilization and remarkable catalytic activity, Cu-N-C type catalysts display great potential for electro-catalysis in CO2 reduction. However, the relationship between the active moiety and catalytic activity of generating high-value C2 products is still unclear, and the explicit screening criteria is scarcity. Herein, based on the first-principle simulation, the structure-performance relationship on Cu-N-C type catalysts has been investigated by modulating the CO2 reduction process as the number of Cu atom (Cu1, Cu2, Cu3) and the ligand environment (B, C, N, O, P, S) changed. We find the adsorption strength of intermediate *CO strongly affect the possibility of C-C coupling, which can be determined by Bader charge on Cu atom, mainly depending on the number of loaded atomic Cu on Cu-N-C catalysts. Furthermore, the Bader charge can be refined by adjusting the coordination atom of Cu, thus optimizing catalytic activity for the CO2 to ethanol. The moderate Bader charge value, between +0.35 and +0.45, enables the catalyst to behave as a potentially excellent activity with low limiting potential for generating ethanol. More importantly, an intrinsic descriptor, composed of the radius, electronegativity, and number of valence electrons of coordination atoms (φ=∑χ∑r*∑np), was established to characterize the catalytic activity of Cu-N(X)-C catalysts for producing ethanol. Two excellent catalysts, Cu3-N2O2 (-0.51 V) and Cu3-N3S (-0.64 V), are screened out for the CO2RR to generate ethanol. This work discloses theoretical basis for catalytic selectivity of C2 products on Cu-N-C catalysts and provides a regulating and screening principle for high performance catalysts to ethanol.

Assembling copper and cerium into TNU-9-type periodic microporous organosilicas for the selective catalytic reduction of NOx by NH3

TNU-9-type periodic microporous organosilicas material containing Ce and Cu was assembled by organic-inorganic hybrid method and then calcined to acquire CuCex@PMO-TNU-9 catalyst. The effect of cerium on the structure-performance relationship was studied. The results indicated that the (CuCex@PMO-TNU-9 x = 1.0, 1.5 and 2.0) catalysts were successfully prepared, whereas CuCe2.5@PMO-TNU-9 was not successfully prepared due to the excess of the precursor resulting in the difference of hydrolysis rate between the organosilane precursor and white carbon black. The CuCe2@PMO-TNU-9 catalyst showed higher NH3-SCR activity than Cu@PMO-TNU-9, which was because that the interaction between Ce and Cu could form Cu2++Ce3+↔Cu++Ce4+ redox cycle, which promoted the oxidation of NO to NO2, forming “fast SCR” reaction. More importantly, CuCe2@PMO-TNU-9 catalyst had excellent the resistance of H2O and SO2 due to the excellent hydrophobicity of the TNU-9 zeolite and the sacrificial site Ce protecting the active site Cu.

Investigation on the pore structure-performance relationship of porous carbon adsorbents for SF6/N2 separation via fine pore modulation

The capture and recovery of SF6 as electron specialty gas from SF6/N2 by adsorptive separation have obvious advantages such as the mitigation of greenhouse effect and resource utilization of waste gas. The comprehensive understanding of pore structure-performance relationship of porous materials is beneficial for guiding the design of highly-efficient adsorbents for separating SF6/N2, but is presently limited. In this work, a series of citric acid (CA) and KOH with different molar ratios are designed to synthesize carbon adsorbents denoted as CAK via a one-step carbonization-activation method and probed for the adsorptive separation of SF6/N2. Characterization results reveal that the micropores in carbon adsorbents are finely tuned from 0.73 to 0.88 nm at an angstrom level through increasing the KOH/CA molar ratios in precursors, and the significant mesopores are formed in CAK4. Static adsorption results indicate that the SF6 adsorptive capacity at low pressure of 10 kPa increases and then decreases with the increasing contents of KOH, and the highest value is obtained in CAK2, while the diffusion rates illustrated from the adsorption kinetics continuously increase. By correlating the pore structures with adsorption capacity of adsorbents, the critical role of micropores with size ≤ 0.9 nm in determining the SF6 capacity at 10 kPa and mesopores in enhancing the mass transfer is quantitatively confirmed. The dynamic breakthrough results of CAKx carbon adsorbents for SF6/N2 separation are well explained with these understandings, which are important for guiding the design of porous adsorbents with high-performance for SF6 capture and recovery.

Photocatalytic CO2 methanation over the Ni/SiO2 catalysts for performance enhancement

CO2 methanation produces synthetic natural gas, which reduces CO2 emission and generates sustainable energy. Exploring effective approach and developing high performance Ni catalysts are the main focus for the reaction. In this study, we report photocatalytic methanation over Ni/SiO2 catalysts. Through physicochemical properties of BET, XRD, H2-TPR and TEM, optical properties of UV–visual light absorbance and light-illuminated H2-TPR, and the performance of photocatalytic methanation, the structure-performance relationship is tentatively discussed. The strong absorbance of light, the small size of Ni nanoparticles and the strong metal-support interaction of the Ni/SiO2 catalysts, as well as the low activation energy of CH4 production, are correlated to the enhanced photocatalytic performance compared to the conventional catalytic performance. The photocatalytic pathway of methanation on Ni nanoparticles are suggested to understand the enhanced performance. The work demonstrates the higher photocatalytic methanation performance than conventional catalytic methanation, which is applicable for other reactions using photo-sensitive catalysts.

Engineered shapes using electrohydrodynamic atomization for an improved drug delivery.

The shapes of micro- and nano-products have profound influences on their functional performances, which has not received sufficient attention during the past several decades. Electrohydrodynamic atomization (EHDA) techniques, mainly include electrospinning and electrospraying, are facile in manipulate their products' shapes. In this review, the shapes generated using EHDA for modifying drug release profiles are reviewed. These shapes include linear nanofibers, round micro-/nano-particles, and beads-on-a-string hybrids. They can be further divided into different kinds of sub-shapes, and can be explored for providing the desired pulsatile release, sustained release, biphasic release, delayed release, and pH-sensitive release. Additionally, the shapes resulted from the organizations of electrospun nanofibers are discussed for drug delivery, and the shapes and inner structures can be considered together for developing novel drug delivery systems. In future, the shapes and the related shape-performance relationships at nanoscale, besides the size, inner structure and the related structure-performance relationships, would further play their important roles in promoting the further developments of drug delivery field. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Impact of Cu complex anions on CuZnAl intercalated hydrotalcite-like catalysts for low-carbon alcohols synthesis from syngas

Elucidating the structure-performance relationship of catalysts for low-carbon alcohols synthesis from syngas is crucial for designing efficient catalysts. In this study, CuO particle size, reducibility, and the number of oxygen vacancies could be adjusted by changing intercalated Cu complex anions, thereby affecting the catalyst's performance. The characterization results indicated that the insertion of [Cu(C2O4)2]2- between ZnAl layered double hydroxide resulted in the largest CuO particles (26.5 nm), leading to an increase in the metallic copper surface area. Consequently, the highest CO conversion (13.0 %) was achieved without altering alcohol distribution. On the other hand, when [Cu(EDTA)]2- was inserted, the catalyst possessed the smallest CuO particle size (8.9 nm), more abundant oxygen vacancies, and enhanced interaction between Cu species and ZnO, which promoted carbon chain growth and resulted in a high C2+OH proportion of 75.8 %. Our study thus provides a new perspective on catalyst structures for the syngas production of low-carbon alcohols.

Exploring the Effects of the Photochromic Response and Crystallization on the Local Structure of Noncrystalline Niobium Oxide.

Niobium oxide (Nb2O5) is a versatile semiconductor material with photochromic properties. This study investigates the local structure of noncrystalline, short-range-ordered niobium oxide synthesized via a sol-gel method. X-ray atomic pair distribution function analysis unravels the structural arrangements within the noncrystalline materials at a local scale. In the following, in situ scattering and diffraction experiments elucidate the heat-induced structure transformation of the amorphous material into crystalline TT-Nb2O5 at 550 °C. In addition, the effect of photocatalytic conditions on the structure of the material was investigated by exposing the short-range-ordered and crystalline materials to ultraviolet light, resulting in a reversible color change from white to dark brown or blue. This photochromic response is due to the reversible elongation of the nearest Nb-O neighbors, as shown by local structure analysis based on in situ PDF analyses. Optical band gap calculations based on the ultraviolet-visible spectra collected for both the short-range-ordered and crystalline materials show that the band gap values reduced for the darkened materials return to their initial state after bleaching. Furthermore, electron energy loss spectroscopy reveals the reduction of Nb5+ to Nb4+ centers as a persistent effect. The study establishes a correlation between the band gap and the structure of niobium oxide, providing insights into the structure-performance relation at the atomic level.

Structure–Performance Relationship of Coal-Based Lubricating Base Oils and Sensitivities to Typical Additives

The relationship between the structure characteristics and performances of coal-based hydrogenation isomeric (CTL) base oil and metallocene-catalyzed coal-based poly-alpha-olefin (mPAO) base oil is clarified in this paper. CTL and mPAO were compared with typical petroleum-based and natural gas-based commercial API III and IV base oils. Pressurized differential scanning calorimetry (PDSC), the rotary bomb oxidation test (RBOT), and a four-ball friction tester were used to evaluate the oxidation stability and lubrication performance of base oils under different working conditions. The sensitivity of different base oils to typical antioxidants and extreme-pressure antiwear agents was compared. In particular, the composition and structure of CTL base oil are clearly different from GTL and mineral base oil. The coal-based CTL and mPAO base oils exhibit commendable viscosity–temperature properties, coupled with low-temperature fluidity, fire safety, and minimal evaporation loss. The lubricating properties, oxidation stability, and sensitivity to extreme-pressure antiwear agents of CTL are close to those of similar base oils. However, the sensitivity of CTL to typical antioxidants is relatively poor. In addition, compared with commercial PAO base oil, mPAO has a lower isomerization degree and fewer isomerization types. The oxidation stability and sensitivity to typical antioxidants of mPAO base oil are comparable with those of commercial PAO base oil, while its lubrication performance and sensitivity to typical extreme-pressure antiwear agents are significantly better than those of commercial PAO base oil.

Enhanced SO2, NO, and Cr (VI) removal by lignin-derived high N-doped activated carbon through one-pot strategy: Structure development, structure–performance relationship and mechanism insight

The production of high-performance activated carbon (AC) is recognized as an essential strategy for the effective utilization of lignin resources. In this work, the N-doped AC was successfully prepared by blending sodium lignosulfonate (SL) and different ratios of FeCl3 through one-pot strategy. The AC structure evolution and performance were obtained by a series of characterization and tests. The results showed that, during the activation process, FeCl3 first complexed with urea and catalyzed the depolymerization of SL, and the rapid pore development was mainly caused by the template, including formed FeCl2, Na2Fe3Cl8 and Na6FeCl8. The ratio of FeCl3/SL adjusts the AC physicochemical texture. AC-3 processed a super total specific surface area and pore volume, respectively up to 2048 m2/g and 1.47 cm3/g. Meanwhile, AC-2 showed a higher nitrogen content of 11.4 %. The as-prepared AC shows super desulfurization, denitrification and Cr (Ⅵ) removal ability. AC-2 displayed maximum sulfur capacity and NO conversion, up to 199.1 mg/g and 42.4 %. This enhanced performance is primarily attributed to the pore structure induced by FeCl3 activation, which provides a foundation for adsorption and catalytic processes, further augmented by the increased active sites due to nitrogen doping. AC-3 achieved an extremely high Cr (VI) adsorption capacity, up to 386.2 mg/g, which was primarily attributed to the redox effect of N-containing and O-containing groups on Cr (VI), in addition, the effect of physical adsorption including pore structure is not neglectable. This study highlights the significant potential of environmentally friendly lignin-based porous carbon materials for removing contaminants in both gas and liquid phases.

Designing asymmetrical TMN4 sites via phosphorus or sulfur dual coordination as high-performance electrocatalysts for oxygen evolution reaction

The development ofhighly efficient oxygen evolution reaction (OER) catalysts based on more cost-effective and earth-abundant elements is of great significance and still faces a huge challenge. In this work, a series of transition metal (TM)embedding a newly-defined monolayer carbon nitride phase is theoretically profiled and constructed as a catalytic platform for OER studies. Typically, a four-step screening strategy was proposed to rapidly identified high performance candidates and the coordination structure and catalytic performance relationship was thoroughly analyzed. Moreover, the eliminating criterion was established to condenses valid range based on the Gibbs free energy of OH*. Our results reveal that the as-constructed 2FeCN/P exhibits superior activity toward OER with an ultralow overpotential of 0.25 V, at the same time, the established 3FeCN/S configuration performed well as abifunctional OER/ORR electrocatalysis with extremely low overpotential ηOER/ηORR of 0.26/0.48 V. Overall, this work provides an effective framework for screening advanced OER catalysts, which can also be extended to other complex multistep catalytic reactions.

Chalcogen Atoms Regulate the Organic Solar Cell Performance of B-N-Based Polymer Donors.

Donor polymers play a key role in the development of organic solar cells (OSCs). B-N-based polymer donors, as new types of materials, have attracted a lot of attention due to their special characteristics, such as high E(T1), small ΔEST, and easy synthesis, and they can be processed with real green solvents. However, the relationship between the chemical structure and device performance has not been systematically studied. Herein, chalcogen atoms that regulate the OSCs performance of B-N-based polymer donors were systematically studied. Fortunately, the substitution of a halogen atom did not affect the high E(T1) and small ΔEST character of the B-N-based polymer. The absorption and energy levels of the polymer were systematically regulated by O, S, and Se atom substitution. The PBNT-TAZ:Y6-BO-based OSCs device demonstrated a high power conversion efficiency of 15.36%. Moreover, the layer-by-layer method was applied to further optimize the device performance, and the PBNT-TAZ/Y6-BO-based OSCs device yielded a PCE of 16.34%. Consequently, we have systematically demonstrated how chalcogen atoms modulated the electronic properties of B-N-based polymers. Detailed and systematic structure-performance relationships are important for the development of next-generation B-N-based materials.

Study on design strategies and on new structure-performance relationships for CO2 capture in gas-liquid hollow fiber membrane contactors

The urgent need for carbon dioxide (CO2) capture technologies motivates this chemical engineering study, which systematically investigates the influence of macroscopic and microscopic structure on the CO2 absorption performance of hydrophobic alumina (Al2O3) hollow fiber membrane (A-HFMs) contactors. Six different A-HFMs prepared using the non-solvent-induced phase separation (NIPS) method with select solvents followed by sintering at 1300°C were then tested for chemical CO2 absorption in an A-HFM contactor using a monoethanolamine (MEA) solution. The hydrophobicity of the coatings applied on the A-HFM surfaces was confirmed by the water contact angle and thermogravimetric (TGA) analysis. Pearson's statistical analysis of a correlation matrix revealed the strength of relationships between nine variables, including outer diameter (mm), inner diameter (mm), percentage of sponge layer (%), pore size (nm), maximum pore size (nm), mechanical strength (MPa), surface porosity (m−1), overall porosity (%), and CO2 absorption flux (mol m−2 s−1). Building upon these findings, this study unveils a novel non-linear function linking three specific microscopic characteristics— pore size, surface porosity, and a geometric sponge layer factor—to CO2 absorption flux, offering valuable insights for optimizing hydrophobic A-HFM design and enhancing CO2 capture efficiency. The A-HFM, characterized by the combination of three factors (higher pore size, increased surface porosity, and a thicker sponge layer), achieved a CO2 absorption flux of 6.36 ×10−3 mol m−2 s−1 at room temperature, showcasing its exceptional performance in capturing CO2. The resulting empirical morphological factor provides a novel approach for enhancing the performance of CO2 absorption through A-HFM design optimization.

Enhanced electrochemical oxidation of 5-hydroxymethylfurfural over tailored nickel nanoparticle assembly

Nickel-based materials are promising electrocatalysts for anodic oxidation of 5-hydroxymethylfurfural (HMF) to value-added 2, 5-furandicarboxylic acid (FDCA). However, their catalytic efficiency is impeded by the sluggish phase transformation of Ni(II) hydroxide to the active Ni(III) oxyhydroxide. Herein, we demonstrate for the first time that the phase transformation kinetics and the HMF oxidation activity of nickel nanoparticles can be modulated by creating self-assemblies with different particle aggregation structures: ordered nanoarrays, disordered nanoarrays, and random aggregates. Notably, the nanoparticle assembly featuring an ordered nanoarray structure exhibits the highest activity, achieving 99.8 % HMF conversion and 99.2 % FDCA yield at 1.36 V. In situ Raman spectroscopy and electrochemical analysis reveal that the ordered nanoarray effectively accelerates the transformation kinetics, attributed to the reduced dehydrogenation barrier of Ni(II) hydroxide as confirmed by density functional theory calculations. This work contributes new insights into the structure-performance relationship of Ni-based catalysts, offering valuable guidance for designing high-performing electrocatalysts.

Defect-Induced All-Solid-State Frustrated Lewis Pair on Metal-Organic Monolayer Accelerating Photocatalytic CO2 Reduction with H2O Vapor.

Understanding the structure-performance relationships of a frustrated Lewis pair (FLP) at the atomic level is key to yielding high efficiency in activating chemically "inert" molecules into value-added products. A sound strategy was developed herein through incorporating oxygen defects into a Zr-based metal-organic layer (Zr-MOL-D) and employing Lewis basic proximal surface hydroxyls for the in situ formation of solid heterogeneous FLP (Zr4-δ-VO-Zr-OH). Zr-MOL-D exhibits a superior CO2 to CO conversion rate of 49.4 μmol g-1 h-1 in water vapor without any sacrificing agent or photosensitizer, which is about 12 times higher than that of pure MOL (Zr-MOL-P), with extreme stability even after being placed for half a year. Theoretical and experimental results reveal that the introduction of FLP converts the process of the crucial intermediate COOH* from an endothermic reaction to an exothermic spontaneous reaction. This work is expected to provide new prospects for developing efficient MOL-based photocatalysts in FLP chemistry through a sound defect-engineering strategy.

First Principles Study of the Structure-Performance Relation of Pristine Wn+1Cn and Oxygen-Functionalized Wn+1CnO2 MXenes as Cathode Catalysts for Li-O2 Batteries.

Li-O2 batteries are considered a highly promising energy storage solution. However, their practical implementation is hindered by the sluggish kinetics of the oxygen reduction (ORR) and oxygen evolution (OER) reactions at cathodes during discharging and charging, respectively. In this work, we investigated the catalytic performance of Wn+1Cn and Wn+1CnO2 MXenes (n = 1, 2, and 3) as cathodes for Li-O2 batteries using first principles calculations. Both Wn+1Cn and Wn+1CnO2 MXenes show high conductivity, and their conductivity is further enhanced with increasing atomic layers, as reflected by the elevated density of states at the Fermi level. The oxygen functionalization can change the electronic properties of WC MXenes from the electrophilic W surface of Wn+1Cn to the nucleophilic O surface of Wn+1CnO2, which is beneficial for the activation of the Li-O bond, and thus promotes the Li+ deintercalation during the charge-discharge process. On both Wn+1Cn and Wn+1CnO2, the rate-determining step (RDS) of ORR is the formation of the (Li2O)2* product, while the RDS of OER is the LiO2* decomposition. The overpotentials of ORR and OER are positively linearly correlated with the adsorption energy of the RDS LixO2* intermediates. By lowering the energy band center, the oxygen functionalization and increasing atomic layers can effectively reduce the adsorption strength of the LixO2* intermediates, thereby reducing the ORR and OER overpotentials. The W4C3O2 MXene shows immense potential as a cathode catalyst for Li-O2 batteries due to its outstanding conductivity and super-low ORR, OER, and total overpotentials (0.25, 0.38, and 0.63 V).

Dual-Strategy Tailoring Molecular Structures of Dopant-Free Hole Transport Materials for Efficient and Stable Perovskite Solar Cells.

Dopant-free hole transport materials (HTMs) are ideal materials for highly efficient and stable n-i-p perovskite solar cells (PSCs), but most current design strategies for tailoring the molecular structures of HTMs are limited to single strategy. Herein, four HTMs based on dithienothiophenepyrrole (DTTP) core are devised through dual-strategy methods combining conjugate engineering and side chain engineering. DTTP-ThSO with ester alkyl chain that can form six-membered ring by the S⋅⋅⋅O noncovalent conformation lock with thiophene in the backbone shows good planarity, high-quality film, matching energy level and high hole mobility, as well as strong defect passivation ability. Consequently, a remarkable power conversion efficiency (PCE) of 23.3 % with a nice long-term stability is achieved by dopant-free DTTP-ThSO-based PSCs, representing one of the highest values for un-doped organic HTMs based PSCs. Especially, the fill factor (FF) of 82.3 % is the highest value for dopant-free small molecular HTMs-based n-i-p PSCs to date. Moreover, DTTP-ThSO-based devices have achieved an excellent PCE of 20.9 % in large-area (1.01 cm2) devices. This work clearly elucidates the structure-performance relationships of HTMs and offers a practical dual-strategy approach to designing dopant-free HTMs for high-performance PSCs.

Machine learning insights into catalyst composition and structural effects on CH4 selectivity in iron-based fischer tropsch synthesis

Fe-based Fischer-Tropsch Synthesis (FTS) enables the selective conversion of syngas into long-chain hydrocarbons, which can be further refined to produce highly demanded liquid fuels and high-value chemical products. However, developing novel heterogeneous catalysts for FTS with desirable performance characteristics is a challenging task, as their performance depends on various factors such as precursor, support material, promoters, pretreatment conditions and the catalyst structures. Thus, it remains difficult to understand the structure-performance relationship of FTS and to optimize the catalyst formulations and operating conditions rationally. By integrating traditional chemistry with machine learning, we herein establish intrinsic correlations among reduction, reaction conditions, phase information and the methane selectivity of Fe-based FTS, using high quality experimental data. The content of the iron phases in the post-reaction phase, particularly χ-Fe5C2, significantly influences the methane selectivity of the catalyst. Four types of additives K, Cu, SiO2, and Ca could effectively suppress the methane selectivity, most likely by promoting or stabilizing the iron carbide phases, indicated by their strong correlation. The machine learned structure-performance relationships offers new insights into the design of Fe-based FTS catalysts, and could guide the further optimization of the preprocessing conditions and various parameter factors to minimize the methane selectivity of FTS.