Conversion Technologies Research Articles

Efficient Conversion of CO2 to Ethanol by Utilizing the Topological Surface States of Rare-Earth Cuprates.

The design of high-performance catalysts for the CO2 reduction reaction (CO2RR) remains a significant challenge in advancing CO2 conversion and storage technologies. In this study, we explored the novel application of topological materials for CO2RR, with a focus on the production of high-value C2+ products. Among 14 lanthanum cuprates, Pr2CuO4 was identified as a promising candidate due to its robust topological surface states (TSS) and potential selectivity for C2+ products. Electrocatalytic experiments demonstrated excellent and stable selectivity, achieving over 67% ethanol production with a current density of up to 220 mA cm-2. Detailed analysis revealed strong interactions between the C p orbital of key intermediates and the Cu dx2-y2 and dz2 orbitals, which are identified as the primary contributors to TSS. These interactions significantly enhanced charge transfer along the desired reaction pathway, indicating that the interplay between the orbitals of key intermediates and TSS-contributing orbitals could be pivotal for developing new paradigms in catalyst design by leveraging topological effects.

Rectifier Fault Diagnosis Based on Euclidean Norm Fusion Multi-Frequency Bands and Multi-Scale Permutation Entropy

With the emphasis on energy conversion and energy-saving technologies, the single-phase pulse width modulation (PWM) rectifier method is widely used in urban rail transit because of its advantages of bidirectional electric energy conversion and higher power factor. However, due to the complex control and harsh environment, it can easily fail. Faults can cause current and voltage distortion, harmonic increases and other problems, which can threaten the safety of the power system and the train. In order to ensure the stable operation of the rectifier, incidences of faults should be reduced. A fault diagnosis technique based on Euclidean norm fusion multi-frequency bands and multi-scale permutation entropy is proposed. Firstly, by the optimal wavelet function, information on the optimal multi-frequency bands of the fault signal is selected after wavelet packet decomposition. Secondly, the multi-scale permutation entropy of each frequency band is calculated, and multiple fault feature vectors are obtained for each frequency band. To reduce the classifier’s computational cost, the Euclidean norm is used to fuse the multi-scale permutation entropy into an entropy value, so that each frequency band uses an entropy value to characterize the fault information features. Finally, the optimal multi-frequency bands and multi-scale permutation entropy after fusion are used as the fault feature vector. In the simulation system, it is shown that the method’s average accuracy is 78.46%, 97.07%, and 99.45% when the SNR is 5 dB, 10 dB, and 15 dB, respectively. And the fusion of multi-scale permutation entropy can improve the accuracy, recall rate, precision, and F1 score and reduce the False Alarm Rate (FAR) and the Missing Alarm Rate (MAR). The results show that the fault diagnosis method has high diagnosis accuracy, is a simple feature fusion method, and has good robustness to working conditions and noise.

Toward Understanding Carboxylate Group Contributions to Mn Oxide Catalysts in the Oxygen-Evolution Reaction.

In contrast to the previous assumption that manganese (hydr)oxides, in the absence of other metal ions, exhibit high overpotentials for catalyzing the oxygen-evolution reaction (OER) under neutral conditions, this study uncovers a more nuanced behavior. We demonstrate that layered manganese oxides, when treated with carboxylate groups, exhibit OER activity at the Mn(III) to Mn(IV) oxidation peak following charge accumulation. Upon the addition of poly(acrylic acid) (PAA), the Mn(III) to Mn(IV) transition occurs at a lower potential. While the current density remains modest, this activity is observed at an extraordinarily low overpotential of just 20 mV in a phosphate buffer solution. We present a detailed mechanistic proposal for OER in this low-overpotential regime, focusing on the Mn(III) to Mn(IV) transition and the surrounding OER environment. Oxygen measurements reveal that at an applied potential of 1.25 V, the turnover frequency (TOF) increases from 2.6 × 10-2 s-1 prior to PAA treatment to 4.7 × 10-2 s-1 post-treatment. However, the Tafel slope increases from 384.76 mV/decade before PAA treatment to 414.30 mV/decade after treatment. The observed reduction in overpotential is attributed to the complex interaction between the OER process and charge accumulation, mirroring key mechanisms in natural systems such as the OEC in photosystem II (PSII). This interplay likely facilitates the low overpotential observed in this system, highlighting the relevance of these bioinspired processes in designing efficient electrocatalysts for OER. These findings provide important insights for the development of highly efficient and robust electrocatalysts for water splitting, with significant implications for the future of energy conversion and storage technologies. By emulating the natural Mn redox processes observed in PSII, our work paves the way for the design of more effective catalysts that operate with minimal energy loss, advancing the potential for sustainable energy solutions.

Mitigating A-Site Segregation in Pyrochlore Oxides: Enhancing Oxygen Evolution Reaction Performance through Surface Engineering.

Significant progress has been achieved in enhancing the oxygen evolution reaction (OER) performance of pyrochloric oxides through geometric and electronic structure regulation. However, the issue of A-site cation segregation in these materials remains underexplored. In this study, Bi2Ru2O7, a promising OER electrocatalyst, is synthesized via a sol-gel method, and its surface is modified using l-ascorbic acid to address Bi3+ segregation. This treatment selectively removes the Bi2O3 passivation layer, inducing an amorphous RuOx layer that forms a heterostructure with crystalline Bi2Ru2O7. This engineered structure significantly enhances catalytic performance, reducing the overpotential to 259 mV at 10 mA cm-2 and maintaining stability after continuous operation for >30 h. Comprehensive characterization, electrochemical testing, and density functional theory calculations reveal that the improvements stem from an increased number of oxygen vacancies and enhanced electron transfer. This work underscores the importance of surface engineering to mitigate A-site segregation, providing a new strategy for optimizing Ru-based pyrochlores in energy conversion technologies.

Compatibility Study of Synthesized Materials for Thermal Transport in Thermoelectric Power Generation

This study investigates the compatibility of synthesized materials for optimized thermal transport within thermoelectric modules. Experimental procedures involved the synthesis of candidate materials followed by characterization using techniques such as scanning electron microscopy, and thermal conductivity measurements. The research employs electrodeposition of HoSbxTex on the synthesized materials using AAo as a template in the electrolyte composed of 2mm TeO2, 2.5mm Bi(No3)3, 0.33mm SeO2, and 0.2m HNO3. Compatibility assessments were conducted within simulated thermoelectric modules to evaluate the materials’ performance under realistic operating conditions. The findings reveal crucial insights into the interplay between material properties and thermal transport mechanisms, guiding the selection and optimization of materials for enhanced thermoelectric power generation. Moreover, this study underscores the importance of tailored material design to achieve synergistic enhancements in both thermal and electrical conductivity, thereby advancing the efficiency and viability of thermoelectric energy conversion technologies. This research contributes to the ongoing efforts to enhance thermoelectric power generation and supports the global transition to sustainable energy systems.

Engineering Lattice Strain in Co-Doped NiMoO4 for boosting Methanol Oxidation Reaction.

Nickel-based molybdates have attracted considerable attention owing to their distinctive isomorphous structure. In this study, pristine NiMoO4 and Co-doped Ni1-xCoxMoO4 were synthesized and investigated for their electrocatalytic activity in methanol oxidation and methanol-assisted water splitting reactions. Through a comprehensive exploration of the structure-property relationship, it was found that the optimal coexistence of α and β molybdate phases, induced by Co doping, led to lattice strain and facilitated the presence of essential catalytic descriptors such as higher oxidation states of Ni and surface oxygen vacancies within the lattice. These factors contributed to the enhanced electrocatalytic activity of Ni0.7Co0.3MoO4 in methanol oxidation and hydrogen evolution reaction. Detailed kinetic studies were conducted to further elucidate the mechanisms involved. Overall, these findings highlight the promising potential of Ni0.7Co0.3MoO4 as an effective catalyst for electrochemical methanol upgrading in conjunction with water splitting, with implications for sustainable energy conversion technologies.

Snapping Endows Magnetoelectric Metamaterials with Passive Power-up Conversion.

Harnessing slowly varying or quasi-static magnetic fields, which typically lack the power to light an LED, to power devices with higher demands seems to be impossible if no additional power is supplied. Obviously, the key to overcoming this challenge is to achieve passive power conversion from low-power inputs into high-power outputs. Here, we propose that snap-through buckling─a mechanical instability phenomenon─within a magnetoelectric metamaterial enables passive power-up conversion. Our experimental results indicate that the instantaneous pulsed output power at snapping remains stable even as the frequency decreases by 100 times and exceeds the maximum magnetic input power by 27 times at a low working frequency of 0.01 Hz. Furthermore, for an array of magnetoelectric metamaterials with varying critical magnetic fields, we demonstrate that a series of pulsed outputs can result in continuous electrical output. We anticipate that these findings will open new avenues for advanced energy conversion technologies, underscoring a pioneering application of mechanical principles in materials science.

Recent Developments in Catalytic CO2‐to‐Ethanol Conversion Technologies

AbstractThis review provides a comprehensive overview of current progress in catalytic technologies for converting CO2 to ethanol, emphasizing the importance of sustainable and environmentally friendly alternatives. A range of methodologies is explored, including thermodynamic analysis, thermocatalytic, electrocatalytic, and photocatalytic approaches, while discussing fundamental reaction mechanisms and catalyst design strategies. Significant advancement has been made in the thermocatalytic hydrogenation of CO2, with mixed metal and metal oxide catalysts achieving selectivities exceeding 90%. However, challenges remain in optimizing catalyst performance for enhanced selectivity and conversion rates. Electrocatalytic reduction offers a promising pathway, focusing on alkaline electrolytes and innovative catalyst designs such as Cu/Au and Al‐Cu/Cu2O. Meanwhile, photocatalytic systems harness solar energy, with various novel photocatalysts showing potential for high efficiency. This review aims to elucidate the current landscape and future perspectives on CO2‐to‐ethanol conversion technologies, highlighting their potential role in sustainable energy solutions.

Electroactive ferrocene-based ionic liquids: transport and electrochemical properties of their acetonitrile solutions

The increasing global demand for energy stimulates the development of advanced energy storage and conversion technologies. Modification of electrolyte with redox-active additives is a promising way to enhance the electrochemical performance of energy storage devices. In this work new electroactive ferrocene-based ionic liquids (Fc-ILs) (N-methyl-N-(ferrocenylmethyl)piperidinium bis(trifluoromethanesulfonyl)imide [PipFcMe][NTf2], N-methyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcMe][NTf2], N-ethyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcEt][NTf2]) were synthesized. The structure of the Fc-ILs was confirmed by NMR and XRD. [PipFcMe][NTf2] and [PyrFcMe][NTf2] demonstrated nearly similar crystal structures consisting of cation and anion columns, while alternating cation and anion layers are stacked in the [PyrFcEt][NTf2] crystal. The effects of the Fc-IL mole fraction and temperature on the transport properties of the acetonitrile solutions of the Fc-ILs have been established. The highest electrical conductivities of the [PipFcMe][NTf2], [PyrFcEt][NTf2] and [PyrFcMe][NTf2] solutions calculated using the Casteel-Amis equation were, respectively, 38.06 ± 0.63, 40.34 ± 0.93 and 41.09 ± 0.58 mS/cm at 348.15 K. The activation energies of conductivity were calculated using the Arrhenius and Vogel-Fulcher-Tamman approaches. The Fc-ILs demonstrated a high electrochemical stability range up to 4.67 V. The introduction of electron-withdrawing substituents into the cyclopentadienyl ring of Fc-ILs shifted the half-wave potential to the positive direction. The diffusion coefficients were calculated using the Randles–Ševčík equation for a quasi-reversible process.

Generative artificial intelligence in hospitality and tourism: future capabilities, AI prompts and real-world applications

ABSTRACT The conversational AI emergence technologies like ChatGPT, Claude AI, and Gemini AI are transforming the hospitality and tourism industries. While existing research explores theoretical applications, a critical gap exists in understanding real-world implementation challenges, prompting strategies, and operational impacts of ChatGPT and other AI applications. This study investigates AI integration patterns, prompt optimization techniques (e.g. Input-Output, Chain-of-Thought, and Tree-of-Thought approach), and implementation strategies through a mixed-methods approach. We conducted a bibliometric analysis of 80 studies using R-Biblioshiny, followed by surveys and interviews with stakeholders, including guests/travelers, managers, and academics. Our empirical analysis measures personalization, user satisfaction, operational efficiency, and research productivity. The results demonstrate that while generative AI can enhance customer experiences and operational efficiency, success depends on selecting appropriate prompting methodologies, ethical considerations, workforce development, and community impact. This research provides an integrated framework for responsible AI adoption while identifying critical areas for future research.

Hydrothermal pretreatment for enhanced thermochemical or biochemical conversion of pharmaceutical biowastes into fuels, fertilizers, and carbon materials.

Pharmaceutical biowastes, rich in organic matter and high in moisture, are typical light industry byproducts with waste and renewable attributes. Thermochemical and biochemical conversion technologies transform these residues into value-added bioproducts, including biofuels, biofertilizers, and bio-carbon materials. Hydrothermal pretreatment effectively removes toxic substances and enhances feedstock for these processes. This review comprehensively examines its role in improving the formation of bioproducts from pharmaceutical biowastes, focusing on (i) upgrading and denitrogenating solid biofuels with better combustion performance; (ii) enhancing biodegradability and gaseous biofuel production via organic matter decomposition; (iii) enriching soluble carbon and nitrogen for liquid biofertilizer; (iv) eliminating antibiotic residues and reducing antibiotic resistance in solid biofertilizers; and (v) stabilizing carbon and nitrogen structures and optimizing pore characteristics for functionalized carbon materials. The review recommends a potential staged thermochemical approach to co-produce nitrogen-enriched liquid biofertilizers and porous carbon materials from pharmaceutical biowastes. Hydrothermal pretreatment emerges as a key technique for facilitating the migration and conversion of essential elements like carbon and nitrogen. This study reveals the potential of hydrothermal pretreatment to address the limitations of pharmaceutical biowastes and offers insights into their valorization.

Determination of biomass energy potential based on regional characteristics using adaptive clustering method

Determining the energy potential of biomass is the first step in selecting the most suitable and efficient energy conversion technology based on regional characteristics. The approach to estimating and determining biomass potential generally uses geospatial technology related to collecting and processing data about mapping an area. Unfortunately, this method is inadequate for simulating the interaction between variables, nor can it provide accurate predictions for the biomass supply chain. As a result, the results obtained from this method tend to be biased and macro, particularly in regions experiencing rapid land-use development. In this paper, the author has developed a clustering methodology with a fuzzy c-means (FCM) algorithm to determine biomass energy potential based on regional characteristics to produce data clusters with high accuracy. Grouping the characteristics of clustering-based areas involves grouping physical or abstract objects into classes or similar objects.

Beyond waste in agriculture: Feedstock characterization for thermochemical conversion based on potato above-ground biomass

Agricultural residues represent a valuable opportunity to develop circular bioeconomic systems centered on biomass. Characterizing this type of biomass can alleviate the pressure on current biomass sources (e.g., in forests and their biodiversity), enhance agricultural waste management, and reduce crop field emissions. Thus, this study aimed to evaluate the potential of agricultural plant-based residues as feedstock for thermochemical conversion processes, focusing on potato above-ground biomass to enhance herbaceous characterization. The gravimetric characterization of this type of biomass revealed a water content of 89 % for potato above-ground biomass with differences per plant section. Biomass abundance was also measured, showing that well-developed leaves and main stems were more plentiful. After 70 days after planting (DAP), maximum plant development was achieved, differing from heights development at 40 DAP. Hence, identifying specific times for residue recovery can help develop strategies for biomass recovery, thereby reducing pretreatment costs following the selection of suitable conversion technologies.

Low-Temperature IR Camouflage Materials by Dual Resonances for Enhanced Thermal Management without Energy Consumption.

Due to the critical importance of carbon neutrality for the survival of humanity, passive thermal management, which manages thermal energy without additional energy consumption, has become increasingly attractive. Camouflage materials offer a promising solution for passive thermal management, as they can dissipate heat through thermal radiation, reducing the need for energy-intensive cooling systems. However, developing effective infrared (IR) camouflage solutions for low-temperature environments and small-sized applications remains a challenge because the low temperatures limit the ability to dissipate radiative energy from the surface. Moreover, conventional IR camouflage materials, typically optimized for single band (5-8 μm), face significant limitations in energy dissipation at lower temperatures, which requires a novel way to increase the energy dissipation without the additional energy consumption. Herein, we present a novel low-temperature IR camouflage material (LICM) designed to address these challenges by employing dual-band resonances in the nondetection bands, 5-8 and 14-20 μm based on the atmospheric transmittance. LICM demonstrated an increase in energy dissipation of 273 and 167% at 250 and 350 K, respectively than the conventional IR camouflage materials. Despite the enhanced dissipation, the LICM maintained an IR signature reduction of around 10% of blackbody radiation, ensuring effective IR camouflage. Thermographic measurements using an LWIR camera (7.5-14 μm) further demonstrated the LICM's superior IR camouflage performance. This dual-band resonance design not only extends IR camouflage to low-temperature environments but also facilitates significant energy savings, making it a key ingredient for broad-scale deployment in areas such as energy conversion, aerospace, and sustainable thermal management technologies.

Effect of lead and zinc composition on the optical and structural characteristics of PbZnS thin films fabricated by spray pyrolysis

In this study, PbZnS thin films with varying concentrations of lead (Pb) and zinc (Zn) were successfully produced using the spray pyrolysis method. The structural, optical and surface properties of the films were systematically investigated as a function of the Pb/Zn ratio. Xray diffraction (XRD) analysis confirmed the polycrystalline nature of the films, showing a cubic zinc blende structure with improved crystallinity as Pb content increased. Initially, with the increase in Pb concentration, larger crystallite sizes and decreased microstress were observed, but with the increase of Pb addition, the formation of secondary phases and the emergence of lattice distortions caused a decrease in grain size and an increase in microstress. Optical measurements showed a tunable bandgap in the range of 3.25 eV to 1.30 eV as Pb content increased. The narrowing of the bandgap is attributed to the lower energy gap of PbS compared to ZnS, which allows for enhanced absorption of longerwavelength light, especially in the visible and near-infrared regions. These findings highlight the potential of PbZnS thin films for optoelectronic applications, where the ability to tune the bandgap and enhance absorption through compositional adjustments is crucial for optimizing device performance. The surface morphology of the PbZnS thin films was analyzed using scanning electron microscopy (SEM). The SEM images showed notable changes in grain size and surface roughness as Pb content increased, with larger grains and a more distinct surface structure observed in films with higher Pb concentrations. This work demonstrates the versatility of spray pyrolysis in fabricating thin films with controllable properties, offering valuable insights for future applications in energy conversion technologies, including solar cells and photodetectors.

Pd1Ni2 Trimer Sites Drive Efficient and Durable Hydrogen Oxidation in Alkaline Media.

Anion-exchange membrane fuel cell (AEMFC) is a cost-effective hydrogen-to-electricity conversion technology under a zero-emission scenario. However, the sluggish kinetics of the anodic hydrogen oxidation reaction (HOR) impedes the commercial implementation of AEMFCs. Here, we develop a Pd single-atom-embedded Ni3N catalyst (Pd1/Ni3N) with unconventional Pd1Ni2 trimer sites to drive efficient and durable HOR in alkaline media. Integrating theoretical and experimental analyses, we demonstrate that dual Pd1Ni2 sites achieve a "*H on Pd1Ni2-HV + *OH on Pd1Ni2-HN" adsorption mode, effectively weakening the overstrong *H and *OH adsorptions on pristine Ni3N. Owing to the unique coordination mode and atomically dispersed catalytic sites, the resulting Pd1/Ni3N catalyst delivers a high intrinsic and mass activity together with excellent antioxidation capability and CO tolerance. Specifically, the HOR mass activity of Pd1/Ni3N reaches 7.54 A mgPd-1 at the overpotential of 50 mV. The AEMFC employing Pd1/Ni3N as the anode catalyst displays a high power density of 31.7 W mgPd-1 with an ultralow anode precious metal loading of only 0.023 mgPd cm-2. This study provides guidance for the design of high-performance alkaline HOR catalytic sites at the atomic level.

Strategies for the Transformation of Waste Cooking Oils into High-Value Products: A Critical Review

Waste cooking oils (WCOs) are generated globally from households, the hospitality industry, and other sectors. Presently, WCOs are mainly employed as feedstock for biodiesel and energy production, strongly depending on the availability of WCOs, which are often imported from other countries. The objective of this review is to give an overall comprehensive panorama of the impacts, regulations, and restrictions affecting WCOs, and their possible uses for producing high-value products, such as bio lubricants, bio surfactants, polymer additives, road and construction additives, and bio solvents. Interestingly, many reviews are reported in the literature that address the use of WCOs, but a comprehensive review of the topic is missing. Published studies, industry reports, and regulatory documents were examined to identify trends, challenges, production statistics, environmental impacts, current regulations, and uses for high-value polymer production. The data collected show that WCOs hold immense potential as renewable resources for sustainable industrial applications that are in line with global carbon neutrality goals and circular economy principles. However, achieving this shift requires addressing regulatory gaps, enhancing collection systems, and optimizing conversion technologies. This comprehensive review underlines the need for collaborative efforts among policymakers, industry stakeholders, and researchers to maximize the potential of WCOs and contribute to sustainable development.

Crystallographic Phase‐Dependent Electrochemical Properties of Layered Hydroxides for Energy Applications.

Layered Hydroxides (LHs) have garnered increasing attention for their versatility and potential in various applications, particularly in energy storage and conversion. These materials exhibit notable chemical tunability and structural flexibility; however, misassignments between common phases—such as layered double hydroxides (LDHs), alpha, and beta phases—are still occasionally encountered, despite the distinct properties of each. This review focuses on the influence of crystallographic phases on the electrochemical properties of LHs, a topic that remains relatively underexplored. We discuss several synthetic approaches that allow for precise tuning of these phases, along with the most suitable characterization techniques, including synchrotron‐based methods, and highlight key spectroscopic features that aid in accurate phase identification. Additionally, we provide an overview of recent work from our group, which underscores the importance of crystallographic phases in shaping the electrochemical behaviour of LHs in alkaline environments, particularly for applications such as the oxygen evolution reaction. A more detailed understanding of these phase‐dependent properties is essential for the rational design of more efficient electrode materials, which could further contribute to the advancement of energy conversion and storage technologies.

Incorporating Indium Oxide into Microplasma Reactor for CO2 Conversion to Methanol.

The clean conversion of CO2 is a strategic issue for addressing global climate change and advancing energy transformation. While the current clean CO2 conversion is limited to the H2 pyrolysis process, using H2O as a proton source is more promising and sustainable. A microplasma discharge method is developed, driven by electricity, and utilized for CO2 conversion with H2O. The microplasma integrates the advantages of high energy density in discharge plasma and microchannel reaction spaces, achieving a rapid resource conversion process of CO2 and water and a high selectivity for methanol production. By further combining In2O3 with microplasma and optimizing the structure of In2O3, is improved the selectivity of methanol production to 86.66%. The methanol production rate reached 72.64mmol g-1 h-¹, which is higher than other clean energy-driven conversion technologies. This work provides a green route for uphill reactions in clean CO2 conversion, offering a new approach for CO2 emission reduction and resource utilization.

Electrocatalysis: From Planar Surfaces to Nanostructured Interfaces.

The reactions critical for the energy transition center on the chemistry of hydrogen, oxygen, carbon, and the heterogeneous catalyst surfaces that make up electrochemical energy conversion systems. Together, the surface-adsorbate interactions constitute the electrochemical interphase and define reaction kinetics of many clean energy technologies. Practical devices introduce high levels of complexity where surface roughness, structure, composition, and morphology combine with electrolyte, pH, diffusion, and system level limitations to challenge our ability to deconvolute underlying phenomena. To make significant strides in materials design, a structured approach based on well-defined surfaces is necessary to selectively control distinct parameters, while complexity is added sequentially through careful application of nanostructured surfaces. In this review, we cover advances made through this approach for key elements in the field, beginning with the simplest hydrogen oxidation and evolution reactions and concluding with more complex organic molecules. In each case, we offer a unique perspective on the contribution of well-defined systems to our understanding of electrochemical energy conversion technologies and how wider deployment can aid intelligent materials design.