Improve Energy Conversion Efficiency Research Articles

Carrier Mobility Modulation in Cu2Se Composites Using Coherent Cu4TiSe4 Inclusions Leads to Enhanced Thermoelectric Performance

Carrier transport engineering in bulk semiconductors using inclusion phases often results in the deterioration of carrier mobility (μ) owing to enhanced carrier scattering at phase boundaries. Here, we show by leveraging the temperature-induced structural transition between the α-Cu2Se and β-Cu2Se polymorphs that the incorporation of Cu4TiSe4 inclusions within the Cu2Se matrix results in a gradual large drop in the carrier mobility at temperatures below 400 K (α-Cu2Se), whereas the carrier mobility remains unchanged at higher temperatures, where the β-Cu2Se polymorph dominates. The sharp discrepancy in the electronic transport within the α-Cu2Se and β-Cu2Se matrices is associated with the formation of incoherent α-Cu2Se/Cu4TiSe4 interfaces, owing to the difference in their atomic structures and lattice parameters, which results in enhanced carrier scattering. In contrast, the similarity of the Se sublattices between β-Cu2Se and Cu4TiSe4 gives rise to coherent phase boundaries and good band alignment, which promote carrier transport across the interfaces. Interestingly, the different cation arrangements in Cu4TiSe4 and β-Cu2Se contribute to enhanced phonon scattering at the interfaces, which leads to a reduction in the lattice thermal conductivity. The large reduction in the total thermal conductivity while preserving the high power factor of β-Cu2Se in the (1-x)Cu2Se/(x)Cu4TiSe4 composites results in an improved ZT of 1.2 at 850 K, with an average ZT of 0.84 (500-850 K) for the composite with x = 0.01. This work highlights the importance of structural similarity between the matrix and inclusions when designing thermoelectric materials with improved energy conversion efficiency.

Energy conversion efficiency improvement of a Stirling type PTR for dual temperature cooling by adopting two active work-recovery phase shifters

Deep space exploration is required to solve the problem of energy acquisition and efficient utilization. Improving energy conversion efficiency is vital to this issue. The Stirling type pulse tube refrigerators (PTR) that work in dual temperature zones play a pivotal role in the field of space detection, and the phase shifter of PTR profoundly affects the conversion efficiency of the exergy to cooling capacity. However, the typical phase shifter causes the acoustic power at the hot end of the cold finger to be dissipated into the form of heat, limiting energy efficiency. With the intention of improving the energy conversion efficiency in the PTR, a novel type of active phase shifter with work recovery on a dual temperature zone PTR is proposed and investigated in this article. Based on the pulse tube refrigerator with two separated cold fingers, inertance tubes with reservoirs, active piston phase shifters, and active work-recovery piston phase shifters have been comparatively investigated. While the refrigerator adopts active work-recovery piston phase shifters, a relative Carnot efficiency of 15.5% is obtained in the 35 K and 85 K temperature zones, which is the highest efficiency ever achieved in these temperature areas.

Synthesis and study of electrochemical properties of Ni-Co-V@PrGO to enhance hydrogen evolution reaction

Hydrogen evolution reaction (HER) is kinetically slow as a necessary half-reaction in water-splitting. It requires high-efficiency electrocatalysts to reduce the overpotential and improve energy conversion efficiency. Transition-metal electrode materials with high stability and efficiency have become the frontiers of energy conversion and storage fields. The present work involves the investigation of transition metals as electrocatalysts for HER. On the other hand, various carbon nanomaterials, including carbon nanotubes, activated carbon, and graphene for high-performance electrocatalysts, have been successfully shown. Still, their performances must be improved (using phosphorus-doped graphene) for wider and more challenging applications. The Ni-Co-V@PrGO was synthesized through a simple method with an amorphous structure that enhanced catalytic activity toward hydrogen evolution reaction with a Tafel slope of 80 and 58 mV dec−1 (counter electrode: Pt) and 85 and 118 mV dec−1 (counter electrode: graphite) in alkaline and acidic media, respectively. Hereupon this research presents a simple and efficient high-performance electrocatalyst for HER.

Four-point bending piezoelectric energy harvester with uniform surface strain toward better energy conversion performance and material usage

Improving the energy conversion efficiency of piezoelectric energy harvesters is of great importance, and one approach is to make more uniform use of the working material by ensuring a uniform strain state. To achieve better performance, this paper presents a four-point bending piezoelectric energy harvester with extensive investigation and modeling to identify the influential parameters. An electromechanical analytical model is presented and verified by experimental data. The frequency-domain method extracts the solutions for a general time-variable force and impact. Four-point bending is compared with the standard cantilever harvesters regarding voltage generation, mechanical strain, and figure of merit. Strain contours are analyzed and interpreted for this innovative approach, and the power generation by the optimal resistance load is studied. Dimensionless parameters are introduced and investigated to find the optimal operating conditions for the four-point bending harvester. Finally, the four-point bending performance and the best figure of merit are discussed with a view to the long-term fatigue life of the harvester. The results show that in the best four-point bending energy conversion conditions; the energy conversion coefficient is more than three times higher than that of typical cantilever energy harvesters. The results also illustrate that the axial strain experienced in a standard cantilever harvester is more than three times higher than that of the four-point bending harvester, suggesting the latter device may have favorable fatigue performance. Overall, the presented piezoelectric harvester has improved energy conversion efficiency and experiences a reduced and uniform surface strain, making it appropriate for high-efficiency energy harvesting systems.

Light, Heat and Electricity Integrated Energy Conversion System: Photothermal-Assisted Co-Electrolysis of CO2 and Methanol.

Strategy that can design powerful photothermal-catalysts to achieve photothermal-effect assisted coupling-catalysis is much desired for the improvement of energy conversion efficiency and redox product value in CO2 electroreduction system. Herein, a kind of bifunctional viologen-containing covalent organic framework (Ni-2CBpy2+ -COF) has been prepared and successfully applied in photothermal-assisted co-electrolysis of CO2 and methanol. Specifically, the FECO (cathode) and FEHCOOH (anode) for Ni-2CBpy2+ -COF can reach up to ≈100 % at 1.9 V with ≈31.5 % saved overall electricity-consumption when the anodic oxygen evolution reaction (OER) is replaced by methanol oxidation. The superior performance could be attributed to the cyclic diquats in Ni-2CBpy2+ -COF that enhance the photothermal effect (ΔT=49.1 °C) to accelerate faster charge transfer between catalyst and immediate species as well as higher selectivity towards desired products as revealed by DFT calculations and characterizations.

Light, Heat and Electricity Integrated Energy Conversion System: Photothermal‐Assisted Co‐Electrolysis of CO2 and Methanol

AbstractStrategy that can design powerful photothermal‐catalysts to achieve photothermal‐effect assisted coupling‐catalysis is much desired for the improvement of energy conversion efficiency and redox product value in CO2 electroreduction system. Herein, a kind of bifunctional viologen‐containing covalent organic framework (Ni‐2CBpy2+‐COF) has been prepared and successfully applied in photothermal‐assisted co‐electrolysis of CO2 and methanol. Specifically, the FECO (cathode) and FEHCOOH (anode) for Ni‐2CBpy2+‐COF can reach up to ≈100 % at 1.9 V with ≈31.5 % saved overall electricity‐consumption when the anodic oxygen evolution reaction (OER) is replaced by methanol oxidation. The superior performance could be attributed to the cyclic diquats in Ni‐2CBpy2+‐COF that enhance the photothermal effect (ΔT=49.1 °C) to accelerate faster charge transfer between catalyst and immediate species as well as higher selectivity towards desired products as revealed by DFT calculations and characterizations.

Shell-shaped active layers for omnidirectional organic photovoltaic cells

For the employment of organic photovoltaic cells in wearable electronic systems, improvements in energy conversion efficiency and omnidirectionality (angular coverage) are highly appreciated. This study aims at those improvements by introducing shell-shaped active layers. The proposed device structures enhance light absorption and angular range through light coupling to guided modes in the active layer. Two shapes, i.e., a triangle and a semicircle, are examined for the shell cross-sections. Numerical simulation using finite-element analysis and finite-difference time-domain methods demonstrates that the devices with the triangular-shell-shaped active layers exhibit an average absorption enhancement of up to 63% for transverse electric (TE)-polarization and up to 32% for transverse magnetic (TM)-polarization when compared with the flat active layers of the same thicknesses. The average enhancements of the semicircular-shell-shaped active layers are found to be slightly lower than those values, with 60% for TE and 28% for TM. The examined structures also show good omnidirectionality with decent absorption up to an 81 deg incidence angle for the triangular-shell-shaped device and up to a 76 deg angle for the semicircular one when TM polarization is considered. These absorption enhancements and improved angular coverages make the proposed structures highly attractive for wearable electronic system applications.

An improved Kalman particle swarm optimization for modeling and optimizing of boiler combustion characteristics

AbstractWith the rapid development of the national economy, the demand for electricity is also growing. Thermal power generation accounts for the highest proportion of power generation, and coal is the most commonly used combustion material. The massive combustion of coal has led to serious environmental pollution. It is significant to improve energy conversion efficiency and reduce pollutant emissions effectively. In this paper, an extreme learning machine model based on improved Kalman particle swarm optimization (ELM-IKPSO) is proposed to establish the boiler combustion model. The proposed modeling method is applied to the combustion modeling process of a 300 MWe pulverized coal boiler. The simulation results show that compared with the same type of modeling method, ELM-IKPSO can better predict the boiler thermal efficiency and NOx emission concentration and also show better generalization performance. Finally, multi-objective optimization is carried out on the established model, and a set of mutually non-dominated boiler combustion solutions is obtained.

Climate change mitigation potentials of biofuels produced from perennial crops and natural regrowth on abandoned and degraded cropland in Nordic countries

Bioenergy expansion is present in most climate change mitigation scenarios. The associated large land use changes have led to concerns on how bioenergy can be sustainably deployed. Promising win-win strategies include the production of perennial bioenergy crops on recently abandoned cropland or on cropland prone to land degradation, as perennial crops typically reduce soil erosion rates. Natural vegetation regrowth is an alternative nature-based solution that can also co-deliver negative emissions and other environmental benefits. In this study, we explore the potential to deploy bioenergy crops in Nordic countries (Norway, Sweden, Finland, and Denmark) on abandoned cropland and on cropland threatened by soil erosion and compare the achievable climate change mitigation benefits with natural regrowth. We found 186 thousand hectares (kha) of abandoned cropland and 995 kha of cropland threatened by soil erosion suitable for bioenergy crop cultivation. The primary bioenergy potential in the region is 151 PJ (PJ) per year, corresponding to 67–110 PJ per year of liquid biofuels depending on biorefinery technology. This has a climate change mitigation potential from −6.0 to −17 megatons of carbon dioxide equivalents (MtCO2eq) per year over the first 20 years (equivalent to 14–40% of annual road transport emissions), with high-end estimates relying on bioenergy coupled to carbon capture and storage (BECCS). On the same area, natural regrowth can deliver negative emissions of −10 MtCO2eq per year. Biofuel production outperforms natural regrowth on 46% of abandoned cropland with currently available biorefinery technologies, 83% with improved energy conversion efficiency, and nearly everywhere with BECCS. For willow windbreaks, improved biorefinery technology or BECCS is necessary to ensure the delivery of larger negative emissions than natural regrowth. Biofuel production is preferable to natural regrowth on 16% of croplands threatened by soil erosion with the current biorefinery technology and on 87% of the land area with BECCS. Without BECCS, liquid biofuels achieve larger climate benefits than natural regrowth only when bioenergy yields are high. Underutilized land and land affected by degradation processes are an opportunity for a gradual and more sustainable bioenergy deployment, and local considerations are needed to identify case-specific solutions that can co-deliver multiple environmental benefits.

Plant-Mimetic Vertical-Channel Hydrogels for Synergistic Water Purification and Interfacial Water Evaporation.

The integration of renewable solar energy-driven interfacial evaporation and photocatalysis has recently emerged as one of the most promising technologies for simultaneous freshwater production and pollutant removal. However, the construction of an advanced integrated system with the merit of a fast supply of water and pollutant molecules remains challenging for efficient solar-driven evaporation and photocatalytic performance. Herein, inspired by the transpiration of plants, we fabricate a biomimetic, vertically channeled polypyrrole/foam-like carbon nitride/poly(vinyl alcohol) hydrogel (PCH) by directional freeze-drying. We prove that the vertically aligned channels not only reduce heat loss and improve energy conversion efficiency but also facilitate the transport of water and organic pollutants to the air-water interface. Benefiting from the advantages above, the PCH evaporator presents a high solar evaporation efficiency of 92.5%, with the evaporation rate achieving 2.27 kg m-2 h-1 under 1 kW m-2 irradiation, exceeding many advanced interfacial solar-driven evaporators. Meanwhile, PCH reaches a degradation efficiency of 90.6% within 1 h when dealing with tetracycline (a typical antibiotic)-polluted water, remarkably higher than that of the hydrogel without vertically aligned channels (68.6%). Furthermore, the as-formed reactive oxygen species effectively kill Gram-positive and Gram-negative bacterial in the source water, achieving the all-round water purification. In an outdoor experiment, after 11 h of sunlight irradiation, the tetracycline degradation efficiency and freshwater production of the PCH evaporator rise to 99.0% and 6.2 kg m-2, respectively. This work highlights the novel biomimetic approach to fabricate multifunctional photothermal materials for simultaneous freshwater production and polluted-water remediation.

Fe7Se8@Fe2O3 heterostructure nanosheets as bifunctional electrocatalyst for urea electrolysis

Water electrolysis for producing hydrogen is considered to be the most feasible means to develop new green energy. Compared with above, urea electrolysis can improve energy conversion efficiency by introducing urea, and can also be used for purification of wastewater rich in urea. In this paper, a bifunctional electrocatalyst with heterostructure, namely Fe7Se8@Fe2O3 nanosheets supported on nickel foam, were synthesized for the first time through typical hydrothermal and partial oxidation processes. Iron cation promotes electron transfer and adjusts electron structure under the synergistic action of selenium and oxygen anion, thus achieving excellent catalytic activity of urea electrolysis. In an alkaline solution of 1 M KOH with 0.5 M urea, the Fe7Se8@Fe2O3/NF catalyst can drive the current density of 10 mA cm−2 with requiring only potential of 1.313 V and overpotential of 141 mV for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), respectively. What is noteworthy is that Fe7Se8@Fe2O3/NF heterostructure is used as bifunctional electrocatalyst to form urea electrolyzer device, which only needs potential of 1.55 V to drive current density of 10 mA cm−2, which is one of the best catalytic activities reported so far, and the electrode couple showed remarkable stability for 15 h. Density functional theory shows that the Fe7Se8@Fe2O3/NF material exhibits the minimum Gibbs free energy for the adsorption of hydrogen. This work provides a new method for exploring novel and environmentally friendly bifunctional electrocatalysts for urea electrolysis.

Atomic layer deposition of ZnO layers on Bi2Te3 powders: Comparison of gas fluidization and rotary reactors

Interface engineering of thermoelectric powder materials via atomic layer deposition (ALD) has attracted significant research interest owing to the dramatic improvement in energy conversion efficiency. Using ALD to uniformly coat ultrathin (a few nanometers) ZnO layers on the microscale irregular shape of bismuth telluride-based powders is a challenge. An ALD reactor that fluidizes or agitates the powders can be adapted for this purpose. In this study, two types of ALD reactors, a gas fluidization reactor and a rotary reactor, were used to coat selenium-doped bismuth telluride powders with ZnO. Uniform and conformal ZnO layers were successfully grown using both the ALD reactors. However, the crystalline structure, particle size distribution, and chemical bonding states of ZnO were affected by reactor type. Pelletization of the ALD-coated powders was performed by spark plasma sintering at a high temperature (500 °C) and pressure (60 MPa). The morphologies of the powders did not change with palletization; however, differences in the chemical states of the ZnO layers on the BTS powders were observed. It was observed that the remnant water molecules and mobile ion species might compensate for the carrier mobility in pellets made of ALD-coated powders.

An electrospun transporter-assisted evaporator with antifouling water channels for solar-driven desalination and water purification

BackgroundInterfacial solar steam generation is a promising, energy-efficient, and environmentally friendly technology in water purification. Most studies currently focus on the design of various light absorbers and improvement of energy conversion efficiency. However, there are few reports about how to enhance evaporation performance and water quality of evaporators in the treatment of oily water and seawater. MethodsHerein, this work demonstrates an electrospun transporter-assisted evaporator with antifouling water channels for water purification and desalination. The graphene oxide/polyacrylonitrile (GO/PAN) nanofibrous membrane as the photothermal layer can convert solar energy into heat for the vaporization of water. By in-situ crosslinking zwitterionic gel on a porous PAN nanofibrous strip as the water channel, the water channel can achieve a superwetting surface, thereby enhancing hydrophilicity and underwater superoleophobicity. FindingsThe evaporator with the zwitterionic gel modified PAN (ZG-PAN) strip demonstrates the stable evaporation rate and prevented the adhesion of organic pollutants, meanwhile decreases the concentration of total organic carbon in the collected water. Additionally, anti-polyelectrolyte effect of the zwitterionic polymer reduces the salt deposition on the evaporation surface and maintains stable desalination performance. Our study provides an effective method to improve solar evaporation performance and product water quality during a long-term oily water or seawater treatment.

Nanofluidic Membranes to Address the Challenges of Salinity Gradient Energy Harvesting: Roles of Nanochannel Geometry and Bipolar Soft Layer.

Researchers are looking for new, clean, and accessible sources of energy due to rising global warming caused by the usage of fossil fuels and the irreversible harm that this does to the environment. Water salinity is one of the newest and most accessible renewable energy sources, which has sparked a lot of interest. Reverse electrodialysis (RED) has been utilized in the past to turn saline water into electricity. NRED, a reverse electrodialysis method utilizing nanofluidics, has gained popularity as nanoscale research advances. Developing and evaluating NRED systems is time-consuming and expensive due to the method's novelty; thus, modeling is required to identify the best locations for implementation and to comprehend its workings. In this work, we examined the influence of bipolar soft layer and nanochannel geometry on ion transfer and power production simultaneously. To achieve this, the two trumpet and cigarette geometries were coated with a bipolar soft layer so that both negative (type (I)) and positive (type (II)) charges could be positioned in the nanochannel's small aperture. After that, at steady state conditions, the Poisson-Nernst-Planck (PNP) and Navier-Stokes (NS) equations were solved concurrently. The findings revealed that altering the nanochannel coating from type (I) to type (II) alters the channel's selectivity from cations to anions. An approximately 22-fold improvement in energy conversion efficiency was achieved by raising the concentration ratio from 10 to 100 for the type (I) trumpet nanochannel. Type (I) cigarette geometry is advised for maximum power output at low and medium concentration ratios, whereas type (I) trumpet geometry is recommended for the maximum power production at high concentration ratios.

Analysis and optimization of self-powered parallel synchronized switch harvesting on inductor circuit for piezoelectric energy harvesting

Due to its strong environmental robustness and high energy density, piezoelectric energy harvesting is considered one of the most promising methods to power wireless sensor nodes under extreme conditions. The interface circuit is essential to a piezoelectric energy harvester to reduce internal energy dissipation, achieve impedance matching, and improve energy conversion efficiency. Existing researches show that a parallel synchronized switch harvesting on inductor (P-SSHI) interface circuit compared with a standard energy harvesting (SEH) circuit can significantly improve the output power. Therefore, this paper proposes a self-powered optimized PSSHI (SP-OPSSHI) circuit, which adopts a new peak detection switching circuit to replace the switches in the P-SSHI circuit. It can realize switch control without an external starting power supply, i.e. cold start. Compared with an existing self-powered PSSHI (SP-PSSHI) circuit, it can effectively eliminate the ‘second inversion’ phenomenon caused by the parasitic capacitors of transistors after the voltage inversion process. The cause and effect of ‘second inversion’ on energy harvesting are analyzed in this study. Then, the working principle and process of the optimized circuit are discussed, and energy harvesting under the ideal state is conducted. Finally, the SP-OPSSHI circuit is developed and tested. The experimental waveforms show that the SP-OPSSHI circuit compared with the SP-PSSHI circuit can significantly reduce the impact of parasitic capacitors in the energy harvesting process. The output performance of the SP-OPSSH circuit is tested with the variation of resistance. The experimental results indicate that the SP-OPSSHI circuit has an optimal load resistance of 350 kΩ, achieving a maximum harvested power being 2.91 times that of the SEH circuit.

Heat transfer, dynamic characteristics and disturbance to water of bubbles generated on vertical surfaces featuring extreme wettability patterns

Surfaces with mixed wettability patterns are one of the potential ways to improve energy conversion efficiency of industrial equipment. It can significantly change the boiling heat transfer proformance of the surface by affecting the bubble dynamics, as well as the flow field properties. Accordingly, this work simultaneously investigates the thermodynamic, bubble dynamics, and water velocity vector field of the bubbles generated on the designed surfaces, through a combination of thermal parameter measurements, high-speed photography, and particle image velocimetry (PIV). The surfaces are designed in six types, and coated by alternating superhydrophilic materials (contact angle of 9.8°) and superhydrophobic materials (contact angle of 154.8°) at intervals with widths of 5 mm, 10 mm, and 15 mm, respectively. The results showed that the different wettability of the pattern at the bubble generation leads to different bubble formation modes, which in turn affects the heat transfer and the initial dynamics of the bubble. The different width of the pattern affects the bubble floatation and water motion. After comparison, it is found that the bubbles have the best heat transfer proformance when they are generated on a superhydrophilic pattern with a width of 15 mm. However, regardless of pattern wettability and width, the bubble frequency, size, and velocity, as well as the water vorticity and velocity, increase with decreasing supercooling, and first increase and then decrease with increasing heat flux. Based on the experimental results, the correlations of bubble velocity and water velocity are modified by introducing the influence factor of wettability patterns. It is tested that it is not only adaptable to the data of this experiment, but can also be generalized to the data of other works.

Triboelectric nanogenerator with a seesaw structure for harvesting ocean energy

In modern times, conventional energy resources are depleting at a rapid pace, and clean renewable energy sources are becoming a research hotspot. In this regard, the triboelectric nanogenerator (TENG) is being used for collecting mechanical energy from the environment. However, the performance of the common solid–solid TENG is often limited by its bulky mechanical structure. Therefore, the present study proposes a novel TENG with the seesaw equal-arm lever structure, which is lightweight and convenient to use. The performance output of the proposed TENG is not limited by its structure. Moreover, it is capable of harvesting the energy of ocean waves in both horizontal and vertical directions. The performance of the proposed TENG was evaluated under different wave conditions using equipment such as motors to simulate the frequency and amplitude of ocean waves. The optimal voltage output achieved using the proposed TENG was up to 1055 V, and the current was up to 72 µA. In addition, a double-sided DSS-TENG was fabricated on the foundation of SS-TENG to exhibit improved energy conversion efficiency. Finally, the SS-TENG was applied successfully to power LED lamps and small hygrometers, which demonstrated that the SS-TENG had good stability and could serve as a feasible tool for large-scale collection of blue ocean energy.

Ferroelectricity-Coupled 2D-MXene-Based Hierarchically Designed High-Performance Stretchable Triboelectric Nanogenerator.

Triboelectric nanogenerators based on the state-of-the-art functional materials and device engineering provide an exciting platform for future multifunctional electronics, but it remains challenging to realize due to the lack of in-depth understanding on the functional properties of nanomaterials that are compatible with microstructural engineering. In this study, a high-performance stretchable (∼60% strain) triboelectric nanogenerator is demonstrated via an interlocked microstructural device configuration sandwiched between silver-nanowire-(Ag-NW) electrodes and hierarchically engineered spongy thermoplastic polyurethane (TPU) polymer composite with ferroelectric barium-titanate-coupled (BTO-coupled) 2D MXene (Ti3C2Tx) nanosheets. The use of MXene results in an increase in the dielectric constant whereas the dielectric loss is lowered via coupling with the ferroelectricity of BTO, which increases the overall output performance of the nanogenerator. The spongy nature of the composite film increases the capacitance variation under deformation, which results in improved energy-conversion efficiency (∼79%) and pressure sensitivity (4.6 VkPa-1 and 2.5 mAkPa-1) of the device. With the quantum-mechanically calculated electronic structure, the device converts biomechanical energy to electrical energy and generates an open-circuit output voltage of 260 V, short-circuit output current of 160 mA/m2, and excellent power output of 6.65 W/m2, which is sufficient to operate several consumer electronics. Owing to its superior pressure sensitivity and efficiency, the device enables a broad range of applications including real-time clinical human vital-sign monitoring, acoustic sensing, and multidimensional gesture-sensing functionality of a robotic hand. Considering the ease of fabrication, excellent functionality of the hierarchical polymer nanocomposite, and outstanding energy-harvesting performance of nanogenerators, this work is expected to stimulate the development of next-generation self-powered technology.

Optimal Reconfiguration of Thermoelectric Generation System Under Heterogeneous Temperature Difference

In view of the low efficiency of thermoelectric generation systems in different regions, this paper designs an optimization and reconfiguration of thermoelectric power generation system under heterogeneous temperature difference (HTD) based on particle swarm optimization (PSO) algorithm, so as to make full use of various thermal energy resources and obtain higher electrical output power, which realize multi-directional utilization of energy. In addition, PSO algorithm is a simple optimization strategy with a straightforward operation mechanism and fewer parameters to control during calculation. The research shows that when TEG array is in multiple HTD states, PSO algorithm has a stronger ability to get rid of local optimization, which can reduce power loss and improve energy conversion efficiency. On this basis, PSO algorithm is used to reconfigure the 15 × 15 symmetric TEG array. The experimental simulation analysis based on MATLAB platform is carried out to verify the feasibility of PSO algorithm.

Phosphorus-doping promotes the electrochemical etching of metals to nanoporous electrodes for efficient and durable overall water splitting

Electrocatalysts play a central role in electrochemical water splitting to store renewable energy in the chemical fuel of hydrogen. Nanoporous metal electrodes are promising to boost hydrogen production efficiency while challenging in synthesis. Here, a phosphorus-doping assisted electrochemical etching strategy is developed to construct highly nanoporous surfaces on metal electrodes, leading to a remarkable catalytic performance for overall water splitting under lab-level or industrial electrolysis conditions. Specifically, the nanoporous FeCoNiCu foil shows 46 times higher electrochemical surface area, lowering the overpotentials by 102 mV for oxygen evolution reaction and 157 mV for hydrogen evolution reaction. The viability of the strategy is further demonstrated in the prevailing industrial electrodes of nickel meshes, enabling a cell voltage of only 1.931 V under the harsh industrial electrolytic condition (80 °C, 30 wt% KOH, and a current density of 500 mA cm−2). It is 126 mV lower than that of a bare nickel mesh-based electrolyzer and corresponds to a ∼4% improvement in energy-conversion efficiency. This work offers a facile and ease-to-scale-up approach for the upgrading of widespread metal electrodes, possessing great prospects in energy conversion and storage devices including electrolyzers, fuel cells, batteries, and supercapacitors.