Ambient Conditions Research Articles

Catalytic reduction of p-nitrophenol and Eosin Yellow by lemongrass tea-stabilized copper nanoparticles

ABSTRACT Green synthesis of nanoparticles for catalytic applications remains of continued interest, especially for reactions that would occur on an industrial scale or that may be of environmental significance. Here, ultrasmall 2.1-nm copper nanoparticles were synthesized under ambient conditions using a copper sulfate pentahydrate precursor and lemongrass extract as a reducing and capping agent. Their potential to act as catalysts was tested using model reactions: the sodium borohydride reduction reactions of p-nitrophenol and Eosin Yellow. Kinetics measurements were obtained with visible time-course spectroscopy and showed that copper nanoparticles effectively catalyzed both reactions. Temperature dependence followed Arrhenius behavior, indicating the catalyst surface was accessible to reactants. Activation energies of 59.2 and 38.5 kJ/mol were obtained for the reduction reactions of p-nitrophenol and Eosin Yellow, respectively. Large frequency factors for both reactions were found, implying large numbers of catalytic sites and/or facilitation of reaction by capping agents. This copper nanoparticle catalyst prepared via green synthesis demonstrates reproducible reduction behavior for two model reactions and observed rate constants that compare favorably with other copper nanoparticle catalysts, particularly in terms of rate constants normalized for available surface area and including catalysts produced via traditional synthetic methods.

Electrochemical Synthesis of Nitrite and Nitrate via Cathodic Oxygen Activation in Liquefied Ammonia.

The electrochemical oxidation of ammonia (NH3) enables decentralized small-scale synthesis of nitrate (NO3-) and nitrite (NO2-) under ambient conditions by directly utilizing renewable energy. Yet, their electrosynthesis has been restricted to aqueous media and low ammonia concentrations. For the first time, we demonstrate here a strategy enabling the direct electrooxidation of liquefied NH3 to NO3- and NO2- by using molecular oxygen, achieving combined Faraday efficiencies above 40%.

Dual Emission and Low-Temperature Afterglow in Xanthone-Dibenzoazepine for High EQE Host-Guest OLEDs with Low-Efficiency Roll-Off.

Research has been driven to demonstrate organic light-emitting diodes (OLEDs) with high efficiency, and in the quest for new materials, thermally activated delayed fluorescence (TADF) emitters have been employed. Preparation of donor-acceptor (D-A) π-conjugates is a useful guideline for developing TADF emitters. TADF emitters have shown excellent progress and high maximum external quantum efficiency (EQEmax) for OLEDs in the recent past; however, they suffer with substantial roll-off resulting in a decrease in their efficiency. In order to have efficient OLED emitters with less efficiency roll-off, we designed a xanthone-amine derivative with twisted electron-rich dibenzoazepine having limited rotation at the donor-acceptor bond. Xan-Azepine shows solvent polarity-dependent fluorescence in the range of 441- 597 nm having a lifetime below 10 ns. At 77 K in Me-THF, a triplet at 557 nm was observed having a decay lifetime of 0.75 s and an afterglow for about 6 s. In powder, it shows dual emission, i.e., fluorescence (490 and 6 ns) and phosphorescence (530 nm and 192 μs) at ambient conditions. The energy difference between the singlet and triplet energy levels of Xan-Azepine is found to be 0.18 eV in the powder sample. Its blend in 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) showed delayed fluorescence with a lifetime of 118 μs at 300 K, while it reduced to 84 μs at 150 K. These observations suggest the TADF nature of Xan-Azepine in its CBP blend. OLED devices of Xan-Azepine showing a turn-on voltage of 2.8 V and a EQEmax of 12% were successfully fabricated. In the doped films of Xan-Azepine (5 wt %) with CBP, a maximum luminescence of 5980 Cd/m2 at a current density of 70 mA/cm2 was obtained, resulting in devices with low-efficiency roll-off (2.75%).

Deep network based approaches to mitigate seasonal effects in SAR images for deforestation monitoring

Abstract. Most deforestation monitoring programs are based on optical images, which are severely affected by clouds, especially in tropical regions. As an alternative, Synthetic Aperture Radar (SAR) data are minimally affected by atmospheric conditions. However, one of the challenges inherent in such approaches is the effect of seasonal rainforest variations over the SAR images. Recently proposed stabilization algorithms mitigate this effect with significant accuracy gains, however, at the cost of higher computational resources, needed to accommodate long temporal SAR image sequences. This work addresses this issue and presents two alternative solutions that attain similar or better accuracy at a much lower computational requirements. One solution is based on a ResUnet, while the second combines an LSTM and a UNet. Both approaches were tested using raw and stabilized pairs as well as raw sequences. Experiments have indicated that both approaches can mitigate the seasonality effect using a much shorter SAR image sequences than modern stabilization methods require. The results with the multitemporal input outperformed those with the preprocessed bitemporal set by 4.3% in Recall, 1.7% in Precision, and 2.7% in F1-Score, also delivering the best deforestation probability maps.

Winter haze amplification by aerosol hygroscopic growth over eastern Indo- Gangetic Plain

Frequent occurrences of widespread winter haze over Northern India largely appear to originate from exceedingly high concentrations of fine particulate matter from anthropogenic emissions. However, the underlying mechanisms driving winter haze in Northern India are not well understood. This study employed a synergy of satellite and reanalysis data from 2006 to 2021 to assess the role of hygroscopic growth of aerosol optical depth in winter haze over the eastern Indo-Gangetic Plain. A method has been developed to extract dry aerosol optical depth from ambient aerosol optical depth to elucidate the origin of winter haze. About 31% of severe haze episodes (aerosol optical depth > 0.85) occurring under ambient humidity conditions decrease to below 5% for dry conditions, indicating the critical role of particle hygroscopic growth. The change in radiative forcing at the top of the atmosphere due to hygroscopic growth is relatively small compared to that at the surface and in the atmosphere, indicating enhanced atmospheric warming. The ubiquitous winter haze over the eastern Indo-Gangetic Plain is exacerbated by hygroscopic growth under high anthropogenic aerosol emissions, further aggravated through aerosol-radiation feedback. These results will be valuable in devising haze forecasts, implementing effective mitigation policies, and representing aerosol hygroscopicity in climate models.

Assessing Crisis Management Tools for Sustainability of Industrial Safety

This study presents a comprehensive risk assessment of ammonia leaks, focusing on the quantitative modelling of hazardous area ranges, concentration dynamics, and thermal radiation effects under varying leakage scenarios using the ALOHA 5.4.7 software. The analysis involves two key scenarios: an ammonia gas leak and a pool fire, each modelled under distinct atmospheric conditions. For the gas leak scenario, ammonia concentrations were mapped across ERPG-defined hazard zones, ranging from low-level irritation zones (ERPG-1) to life-threatening exposure levels (ERPG-3), with maximum concentrations reaching 1500 ppm within a 110 m radius. The second scenario examined the impact of thermal radiation from a pool fire, identifying critical radiation zones where exposure to heat fluxes exceeding 10 kW.m−2 could cause fatal outcomes within 12 m. Despite ALOHA’s strengths in modelling acute exposure risks and providing valuable input for emergency response planning, the study identifies several limitations, particularly regarding the long-term environmental and health impacts of chemical releases and the effects of varying meteorological conditions. These findings suggest that integrating ALOHA with advanced real-time monitoring and AI-based prediction systems could significantly improve its capacity to manage dynamic, rapidly evolving industrial hazards.

Comparative Analysis of Structural, Optical, and Electronic Properties of Nickel Oxide and Potassium‐Doped Nickel Oxide Nanocrystals

ABSTRACTMetal oxide semiconductors, known for their exceptional optical transparency, high carrier mobility, and stability, have found extensive use in emerging technologies such as optoelectronics and energy storage devices. Among all metal oxide semiconductors, nickel oxide (NiO) stands out as a highly favorable candidate due to its p‐type conductivity along with its substantial band gap (3.5–4 eV) for the broad range of applications, including gas sensors, high‐rate Lithium‐ion batteries, high‐performance supercapacitors, and photovoltaic devices. In light of these versatile applications, our current study presents a comprehensive comparative analysis of the structural and optoelectronic properties of NiO and potassium (K)‐doped NiO nanocrystals. The nanocrystals were synthesized using the co‐precipitation route and subsequently annealed at 500°C under ambient conditions. The effect of K doping on the structural and optoelectronic characteristics was systematically examined using various techniques, including x‐ray diffraction, UV–visible spectroscopy, Raman spectroscopy, and Hall effect measurements. To explore the structural characteristics, XRD measurements were performed, which confirm the FCC structure of nanocrystals. The optical property analysis suggested that the formation of the energy level can contribute to reduction of the band gap. A sharp peak at 397 cm−1 is associated with NiO bond in FTIR spectra which verifies the formation of nanocrystals. Moreover, the incorporation of K increases the intensity of the Raman peaks, which provides evidence for the higher degree of crystallinity in doped samples. These results of Raman scattering are in good agreement with XRD outcomes. In addition, the resistivity of NiO nanocrystals decreases monotonically with the increasing K concentration. The results of temperature‐dependent resistivity further demonstrate that electrons required more energy to jump from one polaron state to another in the case of x = 0.01 M and 0.03 M doped Ni0.5‐xKxO samples. The combination of a diminished band gap and enhanced conductivity makes these materials exceptionally promising for applications in optoelectronics and energy storage.

Varying Performance of Low-Cost Sensors During Seasonal Smog Events in Moravian-Silesian Region

Air pollution monitoring in industrial regions like Moravia-Silesia faces challenges due to complex environmental conditions. Low-cost sensors offer a promising, cost-effective alternative for supplementing data from regulatory-grade air quality monitoring stations. This study evaluates the accuracy and reliability of a prototype node containing low-cost sensors for carbon monoxide (CO) and particulate matter (PM), specifically tailored for the local conditions of the Moravian-Silesian Region during winter and spring periods. An analysis of the reference data observed during the winter evaluation period showed a strong positive correlation between PM, CO, and NO2 concentrations, attributable to common pollution sources under low ambient temperature conditions and increased local heating activity. The Sensirion SPS30 sensor exhibited high linearity during the winter period but showed a systematic positive bias in PM10 readings during Polish smog episodes, likely due to fine particles from domestic heating. Conversely, during Saharan dust storm episodes, the sensor showed a negative bias, underestimating PM10 levels due to the prevalence of coarse particles. Calibration adjustments, based on the PM1/PM10 ratio derived from Alphasense OPC-N3 data, were initially explored to reduce these biases. For the first time, this study quantifies the influence of particle size distribution on the SPS30 sensor’s response during smog episodes of varying origin, under the given local and seasonal conditions. In addition to sensor evaluation, we analyzed the potential use of data from the Copernicus Atmospheric Monitoring Service (CAMS) as an alternative to increasing sensor complexity. Our findings suggest that, with appropriate calibration, selected low-cost sensors can provide reliable data for monitoring air pollution episodes in the Moravian-Silesian Region and may also be used for future adjustments of CAMS model predictions.

Selective Adsorption of Lignin Peroxidase on Lignin for Biocatalytic Conversion of Poplar Wood Biomass to Value-Added Chemicals.

Lignin-first biorefineries aim to maximize the valorization of lignin by prioritizing its conversion over other biomass components. This study investigates the selective adsorption of lignin peroxidase (LiP) isozymes from white rot fungi Phanerochaete chrysosporium on lignin, aiming to enhance the biocatalytic conversion of poplar wood biomass into value-added chemicals. The research focuses on the adsorption characteristics of ten recombinant LiP isozymes, particularly PcLiP03, which exhibited the highest adsorption capacity on lignin and negligible adsorption on cellulose. Adsorption isotherms and structural analyses revealed that hydrophobic interactions significantly contribute to the selective adsorption of PcLiP03. Applying PcLiP03 in a continuous stirring cell system effectively converted lignin in unpretreated poplar wood to 2,6-dimethoxy-1,4-benzoquinone under ambient and mild conditions, highlighting its potential for selective lignin depolymerization in integrated biorefineries. This work underscores the importance of enzyme-substrate interactions and offers a promising approach for more efficient and sustainable biomass utilization.

Forecasting atmospheric persistence and implications for the predictability of temperature and temperature extremes

AbstractExtreme temperatures can cause severe disruptions to society, from negative health consequences to infrastructure damage. Accurate and timely weather forecasts contribute to minimising these detrimental effects, by supporting early‐warning systems. In this context, information on the expected performance of the forecasts is valuable. Here, we investigate whether there is a relationship between the persistence of atmospheric circulation patterns in the Euro‐Atlantic sector and forecast skill for temperatures and temperature extremes in Europe. We first apply an objective method to compute the persistence of large‐scale atmospheric patterns in European Centre for Medium‐Range Weather Forecasts (ECMWF) subseasonal retrospective forecasts. We find that the forecasts successfully predict atmospheric persistence up to time‐scales of approximately two weeks. We next investigate the relationship between the persistence of an atmospheric state and the practical predictability of temperature in terms of the error in surface temperature forecasts. The relationship between the two varies depending on season and location. Nonetheless, in a number of cases atmospheric persistence provides potentially valuable information on the practical predictability of temperature. We specifically highlight the cases of wintertime temperature forecasts up to three weeks lead time and wintertime cold spells up to roughly two weeks lead time.

Features of propagation in the atmosphere of nonlinear acoustic disturbances from pulse sources

The features of the propagation of nonlinear pulsed acoustic disturbances in the atmosphere are considered. Data are presented on the experimental observation of the formation of a shock front and the transition of a shock wave into a low-intensity acoustic wave with transformation of the pulse shape and expansion of the front at distances of more than 1000 km under conditions of both spherical and cylindrical propagation. The influence of Kelvin-Helmholtz instability during rapid gas compression on the formation of the shock front structure is discussed. Under atmospheric conditions, such instability significantly affects dissipative processes in the air and forms the front of a nonlinear wave.

Dependence of cyanobacterium growth and Mars-specific photobioreactor mass on total pressure, pN2 and pCO2

In situ resource utilization systems based on cyanobacteria could support the sustainability of crewed missions to Mars. However, their resource-efficiency will depend on the extent to which gases from the Martian atmosphere must be processed to support cyanobacterial growth. The main purpose of the present work is to help assess this extent. We therefore start with investigating the impact of changes in atmospheric conditions on the photoautotrophic, diazotrophic growth of the cyanobacterium Anabaena sp. PCC 7938. We show that lowering atmospheric pressure from 1 bar down to 80 hPa, without changing the partial pressures of metabolizable gases, does not reduce growth rates. We also provide equations, analogous to Monod’s, that describe the dependence of growth rates on the partial pressures of CO2 and N2. We then outline the relationships between atmospheric pressure and composition, the minimal mass of a photobioreactor’s outer walls (which is dependent on the inner-outer pressure difference), and growth rates. Relying on these relationships, we demonstrate that the structural mass of a photobioreactor can be decreased – without affecting cyanobacterial productivity – by reducing the inner gas pressure. We argue, however, that this reduction would be small next to the equivalent system mass of the cultivation system. A greater impact on resource-efficiency could come from the selection of atmospheric conditions which minimize gas processing requirements while adequately supporting cyanobacterial growth. The data and equations we provide can help identify these conditions.

Evaluation of landing procedures for a high-altitude platform with skid-type landing gear based on pilot-in-the-loop simulations

AbstractIn the context of the project HAP, the German Aerospace Center (DLR) is currently developing a solar-powered high-altitude platform. The underlying vehicle is a fixed-wing aircraft that is supposed to be stationed in the stratosphere for 30 days. Due to, among others, low achievable rates of descent, the use of skids as landing gear and its high susceptibility to wind, landing this aircraft is a very challenging task. Hence, it requires a landing procedure specifically tailored to the aircraft’s particularities. Furthermore, this procedure needs to be easy to follow by pilots especially in adverse atmospheric conditions. This paper deals with a pilot-in-the-loop simulation campaign conducted to assess a landing procedure developed for the high-altitude platform in earlier works. Within this campaign, the pilots are supposed to land the aircraft following this developed procedure in atmospheric turbulence conditions. In addition, they also land the aircraft following a second procedure, which is based on a conventional landing. In doing so, the altitude at which a flare is performed and/or the propellers are shut down is varied. Finally, the novel procedure’s overall feasibility from a piloting point of view and its potential to reduce the risks during landing are assessed. The results show that the procedure proves to reduce the risk of inadvertent ground contact of the aircraft payload compartment, which is associated with serious damage to aircraft structure and payload. However, since the novel procedure is challenging for the pilots, some improvements to the procedure are proposed.

Free‐Standing Ultrathin Films of 2D Perovskite for Light‐Emitting Devices Operating at Strong Coupling Regime

AbstractA novel and cost‐effective method for producing free‐standing polyimide films that support a layer of 2D polycrystalline perovskite is presented. This flexible structure can be easily transferred to different substrates of various sizes and roughness, as demonstrated by depositing it on a small dielectric mirror. The experiments confirm that the presence of polyimide thin film does not affect the optical properties of the 2D perovskite, maintaining its integrity under both ambient and cryogenic conditions. Furthermore, the flexible 2D perovskite within an optical microcavity, achieving strong light‐matter coupling at room temperature is successfully embedded. The findings not only extend the frontiers of flexible optoelectronics but also emphasize its importance in improving high‐performance light‐emitting devices.

Insights into the degradation mechanism of Fe-40Ni-15Co superalloy exposed to marine atmospheric and high-temperature conditions

This study investigated the corrosion and oxidation mechanism of the Cr-free Fe-40Ni-15Co superalloy with exposure to a tropical marine atmosphere for one year and a subsequent high temperature of 650 °C for 300 h. The degradation behavior of the samples was evaluated based on surface characterization and analysis. In the tropical marine atmospheres, the corrosion process of the Fe-40Ni-15Co superalloy presented an initial localized type after one month of exposure and gradually developed into uniform. The corrosion products were mainly comprised of Fe2O3 and NiO, suppressing the pitting process. During the high-temperature oxidation process, all samples presented super-parabolic oxidation kinetics. Except for the initial active oxidation due to salt deposits, the corrosion products after atmospheric exposure could significantly enhance the oxidation resistance at 650 °C. An explanation for the degradation mechanism of the Fe-40Ni-15Co superalloy was developed based on the synergistic effects of atmospheric corrosion and high-temperature oxidation.

Anthocyanins stabilization of Hibiscus sabdariffa extract with sepiolite: Analytical and reactive force fields approaches

Anthocyanins are natural pigments responsible for color in fruits and flowers. They are unstable to diverse ambient conditions like pH, light, or the presence of ions. Thus, in industry, several techniques are employed to protect and use anthocyanins. Likewise, ancient Mayas used clay and indigo extract to prepare a pigment known as Maya Blue, resistant to time and chemicals. For this reason, this work aims to characterize the hibiscus extract and sepiolite bio-hybrids created according to Maya methodology and observe the stability of anthocyanins, which are color-responsible in flowers and fruits. Spectral analysis shows that anthocyanins and color were more stable than controls. Powder bio-hybrids show less color change under UV radiation and allochroic behavior in acid or alkaline atmospheres. At the same time, spectroscopy analyses and X-ray diffraction show no chemical interaction between sepiolite and hibiscus compounds. Our molecular dynamics with Reactive Force Fields (ReaxFF) studies reveal a similar behavior. Thus, our method protected the color of anthocyanins, in the temperature range from 15 to 35 °C. The interaction of hibiscus compounds with clay is due to van der Waals forces.

Characteristics of R2019 Processing of MODIS Sea Surface Temperature at High Latitudes

Satellite remote sensing is the best way to derive sea surface skin temperature (SSTskin) in the Arctic. However, as surface temperature retrieval algorithms in the infrared (IR) part of the electromagnetic spectrum are designed to compensate for atmospheric effects mainly due to water vapor, MODIS SSTskin retrievals have larger uncertainties at high latitudes where the atmosphere is very dry and cold, which is an extreme in the distribution of global conditions. MODIS R2019 SSTskin fields are currently derived using latitudinally and monthly dependent algorithm coefficients, including an additional band above 60°N to better represent the effects of Arctic atmospheres. However, the R2019 processing of MODIS SSTskin still has some unrevealed error characteristics. This study uses 21 years (2002–2022) of collocated, simultaneous satellite brightness temperature (BT) data from Aqua MODIS and in situ buoy-measured subsurface temperature data from iQuam for validation. Unlike elsewhere over the oceans, the 11 μm and 12 μm BT differences are poorly related to the column water vapor at high latitudes, resulting in poor atmospheric water vapor correction. Anomalous BT difference signals are identified, caused by the temperature and humidity inversions in the lower troposphere, which are especially significant during the summer. Although the existence of negative BT differences is physically reasonable, this makes the retrieval algorithm lose its effectiveness. Moreover, the statistics of the MODIS SSTskin data when compared with the iQuam buoy temperature data show large differences (in terms of mean and standard deviation) for the matchups at the Northern Atlantic and Pacific sides of the Arctic due to the disparity of in situ measurements and distinct surface and vertical atmospheric conditions. Therefore, it is necessary to further improve the retrieval algorithms to obtain more accurate MODIS SSTskin data to study surface ocean processes and climate change in the Arctic.

Citizen-Based Water Quality Monitoring: Field Testing a User-Friendly Sensor for Phosphate Detection in Global Surface Waters.

Widespread concern over surface water pollution has led to interest in developing easy-to-use accurate tools for citizen-based measurements that provide high spatial and temporal resolution while maintaining accuracy. Excessive anthropogenic phosphate significantly contributes to global eutrophication and necessitates regular on-site phosphate monitoring in surface waters. Traditional instrumentation for quantifying phosphate is labor-intensive, expensive, and performed in laboratories. Existing on-site testing methods relying on phosphomolybdenum blue (PMB) have limited sensitivity and stability under ambient conditions. To overcome these limitations, a novel low-cost, rapid, and user-friendly sensor for citizen-led phosphate monitoring in surface water is introduced and demonstrated with a global sampling campaign. The fast-flow microfluidic device provides user-friendly operation, achieving an environmentally relevant limit of detection (LoD) of 190 ppb, which is near the EPA-recommended maximum for phosphate. The dip-and-read operation reduces procedural steps while delivering accurate sample volume, making it well-suited for citizen-led science initiatives. This sensor exhibits high selectivity and prolonged stability for two months under ambient conditions. The sensor's performance was validated using the industry-standard UV-Vis method with 90% correlation. More than 1000 sensors were deployed in different continents, facilitating phosphate mapping in diverse water sources across multiple continents. The initiative covered much of the globe, including Thailand, Nepal, Brazil, Chile, the USA, and Germany. In some cases, phosphate levels exceeded legislative guidelines by 100-fold. Through the collaboration of citizen scientists, we analyzed regional topography and socioeconomic practices near water sources, identifying potential sources that could contribute to eutrophication in these areas.

Atmosphere-driven metal-support synergy in ZnO/Au catalysts for efficient piezo-catalytic hydrogen evolution

Piezo-catalysis, which leverages mechanical energy to drive chemical reactions, is emerging as a promising method for sustainable energy production. While the enhancement of piezo-catalytic performance through metal-support interactions is well-documented, the critical influence of the synthesis atmosphere during metal-loaded piezo-catalyst preparation has been a notable gap in the field. To this end, we systematically investigate how different atmospheric conditions during the synthesis of catalysts—without gas flow or with Ar, N2 and O2—affect metal dispersion, oxidation states, piezo-carrier dynamics, and electronic structure, and subsequently shape the metal-support interactions and piezo-catalytic activity. ZnO/Au, with Au deposited on ZnO, is selected as the model system, and hydrogen evolution reaction is used as the probe reaction. Our results demonstrate that an oxygen-enriched atmosphere significantly enhances the metal-support interactions, achieving an ultrahigh net hydrogen yield of 16.5 mmol·g–1·h–1 on ZnO/Au, a 3.58-fold increase over pristine ZnO. Specifically, the performance improvements substantially surpass those synthesized under other atmospheric conditions. Conversely, exposure to CO2 transforms the ZnO support into ZnCO3, adversely affecting its catalytic activity. These findings reveal the crucial impact of synthesis conditions on piezo-catalyst performance and thereby open new avenues for optimizing catalyst systems for enhanced sustainability.

Investigation of highly efficient CO2 hydrogenation at ambient conditions using dielectric barrier discharge plasma

The increasing utilization of CO2 for synthesizing high-value fuels or essential chemicals is a potentially effective approach to mitigating global warming and climate change. Compared to thermal catalytic CO2 conversion under hash operating conditions (400∼500°C, 10 MPa), non-thermal plasma can overcome kinetic barriers and trigger reactions beyond thermal equilibrium at ambient temperature and pressure. In this study, the effects of operating conditions (discharge frequency, input power, and gas flow rate) and geometrical parameters (discharge length, discharge gap, and dielectric materials) have been extensively analyzed using typical cylindrical dielectric barrier discharge (DBD) plasma. The discharge characteristics changed by operating conditions (including waveforms of applied voltage and current) are compared, indicating higher applied voltage and lower gas flow rate can strengthen the filamentary discharges. The results demonstrate CO2 conversion rate increases with the increase of applied voltage and the decrease of CO2/H2 ratio, achieving its maximum value of 43.0% at 20 mL/min. The highest energy efficiency of 3771.9 μg/kJ for CO generation is obtained at the applied voltage of 5.5 kV and gas flow rate of 40 mL/min, respectively. Besides, the constructure of plasma reactor also impacts the performance of CO2 conversion. On the one hand, the discharge gap has a significant role in the variation of CO2 conversion and product selectivity, which is attributed to the electric field density and corresponding electron-induced reaction. On the other hand, the circulating water-cooling jacket was used to find out the influence of reaction temperature, which switched the product from CO to CH4. This work will pave the way for a sustainable alternative towards future CO2 conversion and utilization.