Oxide Layer Research Articles

Solid-State Precipitation of Silver Nanoparticles Nucleated during Al Anodizing: Mechanism and Antibacterial Properties.

This study presents an innovative approach to creating antibacterial aluminum surfaces by combining the antibacterial properties of silver nanoparticles (Ag NPs) with the nanoarchitecture of anodized aluminum oxide in one step. An Al-Ag alloy containing 10 wt % Ag was synthesized and anodized in 0.3 M oxalic acid. Ag NPs precipitated in the solid state during anodization, resulting in a porous nanocomposite structure. Comprehensive characterization using SEM, TEM, and EDS revealed a 43 μm thick oxide layer with uniformly distributed nanopores of approximately 100 nm in diameter. Ag NPs with diameters ranging from 2 to 14 nm precipitated dispersed on the surface, inside pores, and within the Al2O3 matrix. Antibacterial properties were evaluated against Escherichia coli. The anodized Al-Ag surface demonstrated robust antibacterial activity after short incubation times (up to 1 × 108 CFU/ml after 3 h). The enhanced antibacterial properties are attributed to the optimal size and distribution of Ag NPs and the potential physical bactericidal effect of the nanoporous structure. This strategy for the precipitation of Ag NPs in the solid state could be used to fabricate high-touch surfaces in hospitals.

Performance Comparison of Al2O3 Gate Dielectric Grown on 4H-SiC Substrates via Thermal and Plasma-Enhanced Atomic Layer Deposition Methods

Abstract This study systematically compared the material and electrical properties of Al2O3 films deposited on n-type 4H-SiC substrates using thermal and plasma-enhanced atomic layer deposition (ALD), referred to as PE-Al2O3 and T-Al2O3, respectively. Atomic force microscopy data indicates that the roughness of Al2O3 deposited on SiC substrates by both ALD procedures is low. X-ray photoelectron spectroscopy analysis suggests that the proportion of hydroxides on T-Al2O3 surfaces is greater than that on PE-Al2O3. Based on O 1s energy loss spectra and fitting of absorption spectra, the bandgap of Al2O3 films ranges from 6.1 to 6.2 eV, with PE-Al2O3 exhibiting a slightly higher bandgap. As for C-V data analysis of MOS capacitors, PE-Al2O3/SiC possesses a lower interface defect density and border traps in oxide layer than T-Al2O3/SiC. Further I-V testing demonstrates that the breakdown field of PE-Al2O3 is 8.7 MV/cm, with leakage current maintained at the order of 10-8 A/cm2. In contrast, T-Al2O3 displays a breakdown field of 7.2 MV/cm and a significant “soft” breakdown. The effective barrier height of PE-Al₂O₃/SiC is determined to be 1.10 eV based on Fowler-Nordheim tunneling mechanism fitting, which is greater than 0.952 eV for T-Al2O3. These results confirm the advantages of using the PEALD method.

KV-class vertical p-n heterojunction rectifier based on ITO/diamond

Indium tin oxide (ITO) layers were sputter-deposited onto commercially available vertical p/p+ diamond structures consisting of 5 μm thick p-type (1.3 × 1016 cm−3) drift layers deposited by chemical vapor deposition on 250 μm thick heavily B-doped (3 × 1020 cm−3) single crystal substrates. The ITO is found to form a type II band alignment allowing Ohmic contact to the p-type diamond and creating a vertical n-p heterojunction. The maximum reverse breakdown of heterojunction rectifiers was ∼1.1 kV, with an on-resistance (RON) of 13 mΩ · cm2, leading to a power figure of merit of 99.3 MW/cm2. The on-voltage was 1.4 V, diode ideality factor was 1.22, with a reverse recovery time of 9.5 ns for 100 μm diameter rectifiers. The on/off ratios when switching from −5 V forward to 100 V reverse were in the range of 1011–1012. This is a simple approach for realizing high performance vertical diamond-based rectifiers for power switching applications.

Effect of Different Heat Treatment Procedures on the Corrosion Behavior of High-Manganese Austenitic Steels

Abstract This study investigates the effects of different heat treatment procedures on the corrosion behavior of high-manganese austenitic steel containing molybdenum. Five samples were prepared, including as-cast and heat-treated specimens, with varying processes such as tempering, single and double solution annealing, and aging. The study focuses on microstructural changes, carbide dissolution, and the formation of protective molybdenum-rich oxides. Microstructural analysis using scanning electron microscopy and X-ray diffraction was conducted to understand phase distribution. At the same time, corrosion resistance was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy. The results reveal that double solution annealing leads to the most homogeneous microstructure and significantly enhances corrosion resistance by forming stable molybdenum oxide layers, underscoring the crucial role of molybdenum oxides in surface protection. Among the samples, the corrosion resistance ranked from best to worst is as follows: double solution-annealed (Ht-5), solution-annealed (Ht-3), aged after solution annealing (Ht-4), tempered (Ht-2), and as-cast (Ht-1). This highlights the crucial role of molybdenum oxides in surface protection. The findings demonstrate the effectiveness of advanced heat treatments in improving the corrosion resistance of high-manganese austenitic steels for industrial applications.

Hot-Pressing of Ti-Al-N Multiphase Composite: Microstructure and Properties

This study focuses on the development and characterization of a bulk Ti-Al-N multiphase composite enriched with BN addition and sintered through hot pressing. The research aimed to create a material with optimized mechanical and corrosion-resistant properties suitable for demanding industrial applications. The composite was synthesized using a powder metallurgy approach with a mixture of AlN, TiN, and BN powders, processed under a high temperature and pressure. Comprehensive analyses, including microstructural evaluation, hardness testing, X-ray tomography, and electrochemical corrosion assessments, were conducted. The results confirmed the formation of a multiphase microstructure consisting of TiN, Ti₂AlN and Ti₃AlN phases. The microstructure was uniform with minimal porosity, achieving a hardness within the range of 500–540 HV2. Electrochemical tests revealed the formation of a passive oxide layer that provided moderate corrosion resistance in chloride-rich environment. However, localized pitting corrosion was observed under extreme conditions. The study highlights the potential of a BN admixture to enhance mechanical and corrosion-resistant properties and suggests directions for further optimization in sintering processes and material formulations.

Design of Litchi-Like Al/PTFE with Superior Reactivity and Application in Solid Propellants.

The combustion efficiency and reactivity of aluminum (Al) particles, as a crucial component in solid propellants, are constrained by the inert oxide layer aluminum oxide (Al2O3). Polytetrafluoroethylene (PTFE) can remove the oxide layer, however, carbon deposition generated during the reaction process still limits the reaction efficiency of Al/PTFE fuel. Here, a litchi-like Al/PTFE fuel with the nano-PTFE islands distributed on the Al particles surface is successfully designed, based on localized activation and synergistic reaction strategies, to solve the Al2O3 layer and carbon deposition. This unique PTFE-coated structure can achieve localized activation of Al by surface etching, creating reaction channels, and exposing the active Al. Such a channel network promotes the circulation of fluorine and oxygen, stimulating the synergistic reactions of Al-F and Al-O and energy output. Regulating the PTFE content can maximize the elimination of carbon deposition and achieve the full combustion reaction of Al/PTFE. The maximum flame area and pressure output of the litchi-like Al/PTFE fuel increased by 241.9%, 734.7%, 118.4%, and 265.2%, respectively, compared with traditional physical mixture and core-shell structure Al/PTFE fuels. The localized activation and synergistic effects of litchi-like structure effectively transform carbon waste into a valuable resource, introducing a novel approach for the propellants.

Fire Performance Comparison of Expanded Polystyrene External Thermal Insulation Composites Systems and Expandable Graphite-Modified Surface Covers at Different Scales

Numerous fire disasters have involved thermoplastic expanded polystyrene (EPS) external thermal insulation composite systems (ETICS) on building façades. This study evaluates the flame-retardant efficiency of expandable graphite (EG)-blended EPS ETICS across different scales: micro-scale thermogravimetric (TG) analysis, small-scale bench tests, and large-scale LEPIR 2 tests. TG analysis confirmed EG’s primary role as a physical intumescent, with no significant chemical interactions detected. While EG effectively reduced heat penetration in both small-scale and large-scale fire tests, challenges arose from char layer detachment and oxidation at elevated temperatures (exceeding 540 °C). Despite these limitations, the EG-treated façade exhibited significantly lower peak temperatures compared to the untreated control in the large-scale LEPIR 2 test, with a measured temperature difference of approximately 470 °C. These findings demonstrate the potential of EG to enhance the fire safety of EPS ETICS. The small-scale test bench proved effective for preliminary material screening, providing valuable insights into ignition resistance and flame-retardant properties before proceeding to more resource-intensive large-scale evaluations.

Hydrogen generation through metal waste corrosion: a systematic investigation on old/post-consumer scrap Al6063-series alloy

In this study, aluminum-based wastes are used as energy carriers for on-demand hydrogen production through sustainable, eco-friendly, and cost-effective controlled electrochemical corrosion in aqueous solution. The electrochemical process is very effective because it (i) uses waste metals to produce hydrogen, (ii) corroborates to circular economy, (iii) produces high purity hydrogen, (iv) is based on simple hydrolysis reaction of metals in relevant solutions, (v) electricity is not required and (iv) recovers part of the chemical Gibbs energy of the electrochemical corrosion usually entirely lost in the environment. We systematically studied the generation of hydrogen from industrial waste Dust Scrap Aluminum Alloy (DSAA) belonging to Al 6063 series for the first time. The process is investigated in a novel hand-made batch reactor with a low-cost commercial body suitable to an easy scale-up. Kinetics of DSAA hydrolysis reaction was explored by measuring the variation of aluminium ion concentration at different immersion times through Inductively Coupled Plasma (ICP) and weight loss measurements at different temperatures and NaOH catalyst concentrations. The effect of hydrolysis reaction on the composition and morphology of the metal surfaces in terms of formed oxide layers was studied in detail using Optical Polarizing Microscopy (OPM), Energy dispersive X-ray (EDX) and Scanning Electron Microscopy (SEM) techniques. The criteria used to evaluate the hydrogen reactor performance were hydrogen (i) yield and (ii) production rate. The experimental results showed that a strong increase in NaOH concentration (from 0.75 to 5 M) corresponding to a slow increase in hydrolysis reaction temperature (from 38.8 to 49.9 °C) lead to an improvement in hydrogen generation rate of one order of magnitude, i.e. from 35.71 to 421.41 ml/(g∙min). Low but constant rate of hydrogen can be generated for longer times at low NaOH concentrations (0.75 M), while fast and variable hydrogen generation rate occurs at higher concentrations (5 M) in short times. In the case study of Al 6063 series waste scrap, the hydrolysis reactor parameters can be regulated to deliver hydrogen generation rates from 35.71 to 421.41 ml/(g min) according to requirements. We expect that the results presented in this work will encourage researchers to study the possible use of other metal-based and multi-material plastic/metal wastes thermodynamically prone to electrochemical corrosion process as possible source of hydrogen.Graphical

Direct observations of nucleation and early-stage growth of Au-catalyzed GaAs nanowires on Si(111).

Developing a reliable procedure for the growth of III-V nanowires (NW) on silicon (Si) substrates remains a significant challenge, as current methods rely on trial-and-error approaches with varying interpretations of critical process steps such as sample preparation, Au-Si alloy formation in the growth reactor, and nanowire alignment. Addressing these challenges is essential for enabling high-performance electronic and optoelectronic devices that combine the superior properties of III-V NW semiconductors with the well-established Si-based technology. Combining conventional scalable growth methods, such as Metalorganic Chemical Vapor Deposition (MOCVD) with in situ characterization using Environmental Transmission Electron Microscopy (ETEM-MOCVD) enables a deeper understanding of the growth dynamics, if that knowledge is transferable to the scalable processes. We report on successful epitaxial growth of Au-catalyzed GaAs NWs on Si(111) substrates using micro-electromechanical system (MEMS) chips with monocrystalline Si-cantilevers in both conventional MOCVD and ETEM-MOCVD systems. The conventional MOCVD provided a framework for initial parameter tuning, while ETEM-MOCVD offered valuable insights into early nucleation and catalyst-substrate interactions. Our findings show that nucleation is significantly influenced by the removal of native oxide layers and the initial formation of the Au-Si alloy. Our in situ studies revealed different NW-substrate interfaces, essential for optimizing the epitaxial growth process. We identified three typical configurations of NW "roots", each impacted by growth conditions and preparation steps, affecting the structural and potentially the optical properties of the NWs. Similarly, doping from the Si-substrate may affect both optical and electrical properties; however, compositional analysis revealed no traces of Si in NWs post-nucleation and a small amount in the catalytic droplet. Our research highlights the importance of in situ studies for a comprehensive understanding of nucleation mechanisms, paving the way for optimizing III-V NW growth on Si substrates and developing high-performance III-V/Si devices.

Selective Isolation of Surface Grain Boundaries by Oxide Dielectrics Improves Cd(Se,Te) Device Performance.

Cd(Se,Te) photovoltaics (PV) are the most widely deployed thin-film solar technology globally, yet continued efficiency improvements are stymied by challenges at the device hole contacts. The inclusion of solution-processed oxide layers such as AlGaOx in the contact stack has yielded improved device open-circuit voltages (VOC) and fill factors (FF). However, contradictory mechanisms by which these layers improve the device properties have been proposed by the research community. We demonstrate in this work that an underappreciated property of such spin-coated layers is the preferential deposition at grain boundaries, a process that isolates the grain boundaries during contact metallization. The effects of grain-boundary isolation are probed by varying the coverage of solution-processed AlGaOx "barrier" layers on the Cd(Se,Te) surface, quantified by scanning Auger microscopy. Examining coverage-dependent VOC and FF, it was observed that isolating the grain boundaries during metallization is sufficient to prevent damage to the absorber that occurs in devices lacking a barrier layer, while additional coverage contributes to the increased series resistance. Such an effect is agnostic to the material used as a barrier layer, as long as the material does not itself damage the absorber. Spin-coated SiOx was used in place of AlGaOx for an equally beneficial effect. This grain-boundary isolation phenomenon is also observed during Mo deposition and in absorbers that have been contacted with a nitrogen-doped ZnTe layer. The mechanisms by which metallization may degrade the absorber are discussed, as are contact design strategies leveraging barrier layers, which may lead to improved device efficiencies.

EFFECT OF FLUX APPLICATION DURING IN-SITU CASTING AS A DIRECT RECYCLING OF ALSI7MG ALUMINIUM ALLOY MACHINING CHIPS

Recycling aluminium (Al) waste by secondary smelting production saves 95% energy had encourages a new alternative recycling technique known as the in-situ casting or melting to transform waste into product directly. Therefore, aluminium (AlSi7Mg) machining chips with flux addition were heated for 30 minutes in a laboratory furnace at 650°C and 700°C. The physical of Al chips turned from sparkling silvery grey to dusty grey after being heated indicating oxidation. The machining chips had partially melted and fused together however being interrupted by thin oxide layer. Scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) reveal the Al and oxygen (O), while x-ray diffaction (XRD) analysis confirmed aluminium oxide (Al2O3) present in the fused Al chips.

Characterization of Additively Manufactured Titanium-Based Alloy with a Micro-Arc Oxidation Coating and Overlying Polyurethane Layer

Titanium alloys are widely used in the aerospace, automotive, chemical, and biomedical industries due to their excellent corrosion resistance, mechanical properties, and biocompatibility. However, the surface properties of titanium alloys are often insufficient to meet the increasingly complex requirements of certain applications. Therefore, enhancing the surface performance of titanium alloys in physiological environments has become a key focus of research. In this study, a porous oxide layer was generated on the surface of a titanium substrate through micro-arc oxidation (MAO). This layer served as an intermediate layer for a subsequently deposited polyurethane (PU) coating, providing a strong foundation for adhesion. The high porosity of the MAO layer not only facilitated the adhesion of the PU coating but also protected the titanium alloy, further enhancing its corrosion resistance. The surface microstructure after MAO treatment and the morphological changes after application of the PU coating were characterized using scanning electron microscopy. The PU layer uniformly covered the surface of the MAO layer, significantly improving the smoothness and uniformity of the surface. The increase in surface smoothness due to the PU coating on top of the MAO layer was verified through white light interferometry. Additionally, surface hydrophobicity was assessed through water contact angle measurements. The PU layer over the MAO coating significantly enhanced the hydrophobicity of the titanium alloy’s surface, which is crucial for reducing biofouling and improving the effectiveness of biomedical implants. Finally, electrochemical analysis was conducted to study the corrosion resistance of the titanium alloy after MAO and PU treatment. The titanium alloy with an MAO–PU composite coating exhibited the highest corrosion resistance. The findings revealed that the combination of the MAO layer and PU coating provides an excellent multifunctional protective layer for titanium alloys, not only enhancing their durability but also their ability to adapt to physiological and harsh environments.

The Effect of BEOL Design Factors on the Thermal Reliability of Flip-Chip Chip-Scale Packaging

With the development of high-density integrated chips, low-k dielectric materials are used in the back end of line (BEOL) to reduce signal delay. However, due to the application of fine-pitch packages with high-hardness copper pillars, BEOL is susceptible to chip package interaction (CPI), which leads to reliability issues such as the delamination of interlayer dielectric (ILD) layers. In order to improve package reliability, the effect of CPI at multi-scale needs to be explored in terms of package integration. In this paper, the stress of BEOL in the flip-chip chip-scale packaging (FCCSP) model during thermal cycling is investigated by using the finite-element-based sub-model approach. A three-dimensional (3D) multi-level finite element model is established based on the FCCSP. The wiring layers were treated by the equivalent homogenization method to ensure high prediction accuracy. The stress distribution of the BEOL around the critical bump was analyzed. The cracking risk of the interface layer of the BEOL was assessed by pre-cracking at a dangerous location. In addition, the effects of the epoxy molding compound (EMC) thickness, polyimide (PI) opening, and coefficient of thermal expansion (CTE) of the underfill on cracking were investigated. The simulation results show that the first principal stress of BEOL is higher at high-temperature moments than at low-temperature moments, and mainly concentrated near the PI opening. Compared with the oxide layer, the low-k layer has a higher risk of cracking. A smaller EMC thickness, lower CTE of the underfill, and larger PI opening help to reduce the risk of cracking in the BEOL.

Heterostructure Based of Ti-TiO2(NW)/rGO Hybrid Materials for Electrochemical Applications

This study investigated a hybrid electrode based on titanium/titanium dioxide nanowires/reduced graphene oxide (Ti-TiO2(NW)/rGO) that was developed in two stages. The Ti-TiO2(NW)/rGO was obtained by hydrothermal treatment in a mixed solution of H2O2 and melamine for Ti-TiO2 support, followed by a simple spin-coating deposition method and thermal oxidation in a controlled atmosphere of nitrogen gas (99%). The as-prepared structures of electrodes were characterized using ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). In addition, the electrochemical behavior was assessed by cyclic voltammetry (CV) in a 1M HNO3-supporting electrolyte and in the presence of 4 mM K4Fe(CN)6 3H2O to determine the electroactive surface area and apparent diffusion coefficient of the hybrid electrode. The development of the Ti-TiO2(NW)/rGO hybrid electrode provides a sensitive method for photo-electrooxidation of doxorubicin due to exploiting the synergistic and remarkable properties of the nanowires of TiO2 and of reduced graphene oxide (rGO) layer on the electrode surface.

Phosphoric Acid Anodizing Effect on Morphology and Corrosion Resistance of Nanostructured Anodic Oxide Layers on 6061 Aluminum Alloy

Phosphoric Acid Anodizing Effect on Morphology and Corrosion Resistance of Nanostructured Anodic Oxide Layers on 6061 Aluminum Alloy

Dynamic-Wetting Liquid Metal Thin Layer Induced via Surface Oxygen-Containing Functional Groups.

Enhancing the wettability of liquid metals (LMs) to address their high surface tensions is crucial for practical applications. However, controlling LMs wetting on various substrates and understanding the underlying mechanisms are challenging. Here, we present a facile dynamic-wetting strategy to modulate eutectic gallium-indium (EGaIn) wettability via chemical surface modification, spontaneously forming a stable and thin (∼18 μm) EGaIn layer. Polymer substrates exhibiting varying EGaIn wetting behaviors can be categorized by their sliding angles and adhesion force. X-ray photoelectron spectroscopy results demonstrate that the dynamic-wetting process occurs only on surfaces with sufficient oxygen-containing functional groups (content ≥18%) and confirm coordination interactions between the EGaIn oxide layer and surface functional groups. Furthermore, in EGaIn thermal management systems, the heat transfer rate in the wetting group is increased by up to 20% compared to that of the nonwetting group. This work will hasten the application of LMs in flexible circuits and thermal management.

Coupling Influence of pH and Cl- on the Corrosion Evolution of Passivated Q355B Steel in Simulated Concrete Pore Solution.

Electrochemical tests combined with surface characterization techniques were used to investigate the corrosion evolution of passivated Q355B steel under the dual action of pH and chloride. The results show that the Q355B passivation film in simulated concrete pore solution is the amorphous oxide layer, and pH and Cl- have closely coupled effects on Q355B corrosion. Meanwhile, the impact of pH is more significant: the decrease in pH shifts from pitting to uniform corrosion. Furthermore, we found that chloride-induced defects in the passivation film and the Cl- congregate phenomenon jointly controlled the pitting.

Oxide layer growth on silicon substrates: effects of temperature and surface preparation

В работе исследуется процесс роста оксидных слоев на кремниевых подложках в контролируемых температурных условиях. Кремниевые пластины окисляли в печи в течение двух часов при температуре от 300°С до 1100°С. Минимальные изменения поверхности наблюдали при температуре ниже 800°C, тогда как при температуре выше 800°C заметные изменения цвета указывали на значительные эффекты окисления. Перед оксидированием кремниевые подложки подвергали тщательной очистке ацетоном, аммиачной перекисью водорода и плавиковой кислотой (HF) с последующей промывкой деионизированной водой. Толщину оксидных слоев измеряли с помощью эллипсометрии. Кроме того, для анализа оксидных слоев использовали инфракрасную спектроскопию с преобразованием Фурье (FTIR). Для каждой температуры получены FTIR-спектры, показывающие данные по поглощению и волновому числу. В частности, мы сосредоточили внимание на оптической плотности в диапазоне от 1000 до 1300 см−1 и изучили ее зависимость от температуры. Наши результаты проливают свет на взаимосвязь между поглощением и температурой, предоставляя ценную информацию о динамике роста оксидного слоя на кремниевых подложках.

Charge-to-spin conversion at argon ion milled SrTiO3/NiFe hetero-interfaces

Two-dimensional electron gases (2DEGs) at perovskite oxide interfaces, such as strontium titanate (STO), have garnered significant attention due to their induced ferromagnetic (FM), spin–orbit coupling, and superconducting properties. The 2DEG, formed at the interface between STO and either insulating oxides or reactive metals, exhibits efficient charge-to-spin interconversion in STO/NM(non-magnetic)/FM structures. The insulating oxide layer at the STO interface attenuates the spin currents injected into the ferromagnet. In contrast, the metallic layers facilitate efficient spin current injection but suffer from spin current diffusion. Here, we present an approach to overcome these challenges by directly creating a 2DEG at the STO surface through Ar+ ion bombardment. This method enables efficient spin-to-charge conversion without an intermediate NM layer. Our experimental and simulation results demonstrate the generation of unconventional spin currents at the STO(Ar+)/NiFe (Permalloy) interface. Our findings may enable applications of complex oxide and ferromagnet interfaces for efficient charge-to-spin conversion, paving the way for low-power, room-temperature oxide-based spintronic devices.

Liquid Metal Nanobiohybrids for High-Performance Solar-Driven Methanogenesis via Multi-Interface Engineering.

Nanobiohybrids for solar-driven methanogenesis present a promising solution to the global energy crisis. However, conventional semiconductor-based nanobiohybrids face challenges such as limited tunability and poor biocompatibility, leading to undesirable spontaneous electron and proton transfer that compromise their structural stability and CH4 selectivity. Herein, we introduced eutectic gallium-indium alloys (EGaIn), featuring a self-limiting surface oxide layer surrounding the liquid metal core after sonication, integrated with Methanosarcina barkeri (M. b). The well-designed M. b-EGaIn nanobiohybrids exhibited superior performance, achieving a maximum CH4 yield of 455.64 ± 15.99 μmol g-1, long-term stability across four successive 7-day cycles, and remarkable CH4 selectivity of >99%. These improvements stem from enhanced proton-coupled electron transfer involving hydrogen atoms at the core-shell interface, further facilitated by the elevated expression of hydrogenases at the abiotic-biotic interface. This study provides an insightful concept for nanobiohybrid design through multi-interface engineering, advancing sustainable and scalable CO2-to-biofuel conversion under ambient conditions.