Next Energy最新文献

The employment of limitless solar energy via semiconductor-facilitated photocatalysis represents a sustainable strategy for addressing the worldwide energy crisis and escalating environmental concerns. Thus, the advancement of effective photocatalysts represents a significant approach in addressing the energy crisis and environmental challenges. Spinel ferrites, with the general formula of MFe₂O₄ (M is a divalent metal ion such as Mg²⁺, Mn²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺, etc.), have attracted considerable research interest. Interesting physicochemical properties such as narrow bandgap, magnetic recyclability, large surface area, excellent photoactivity, non-toxicity, earth-abundance, easy synthesis, stability, and other exciting properties have seen spinel ferrites emerged as suitable candidates for photocatalytic hydrogen fuel generation. For these reasons, this review attempts to provide an overview of the application of spinel ferrites in photocatalytic hydrogen fuel generation. Herein, latest research conducted in the last decade on the use of spinel ferrite as main and co-catalyst in photocatalytic hydrogen production has been reviewed. Attention has been paid to the crystal structure, prospects and shortcomings as photocatalysts, and synthesis methods, including advantages and disadvantages of various synthesis approaches of spinel ferrites. Moreover, the pathways to improve the performance and efficiency of spinel ferrites for effective water splitting are highlighted in this review. Finally, current challenges, future outlook, suggestions and research gaps in the use of spinel ferrites in photocatalytic hydrogen evolution reaction have also been highlighted. The primary objective of this review is to demonstrate that spinel ferrites are regarded as a significant semiconductor photocatalyst due to their efficient absorption of visible light, suitable band alignment, and magnetic recyclability. This review offers a thorough understanding of spinel ferrite-based photocatalysts, encompassing recent research discoveries and progresses. It is envisioned that further investigations should focus on improving photocatalytic performance of spinel ferrites via construction of heterojunction and modifying synthesis processes.

This overview is designed to highpoint the existing field state of graphene and derived nanocomposites towards most demanding energy devices and systems. Recently, adopting efficient energy conversion and storage systems for technical practices have attained increasing research focus. Owing to unique structure, microstructure, and methodological features, graphene nanomaterials have been focused towards advanced systems like lithium ion batteries, supercapacitors, and fuel cells. Graphene nanocomposites have been recognized for high surface area, electron transference, charge capacity, specific capacitance, charge-discharge capabilities, cyclability, power conversion efficiency, fuel cell parameters, and competent features. In addition, specific features of graphene nanocomposites include exceptional microstructure and mechanical, thermal, and chemical reliability characteristics. In spite of indispensable characteristics of graphene nanocomposites, several processing and property challenges need to be resolved to achieve high-tech graphene nanocomposites towards advanced energy storage/conversion devices and systems.

The versatile applications of flexible perovskite solar cells (PSCs) have made them promising energy-harvesting devices in our daily lives. The electron transport layer (ETL)-free PSCs offer a flexible approach for harnessing energy while adding a bifacial approach that can further improve the device performance. In our study, we have optimized ETL-free bifacial PSCs via simulation by selecting the suitable front transparent electrode (FTE), hole transport layer (HTL), and rear transparent electrode (RTE). Our investigation reveals that a potential well-like structure, associated with a small conduction band offset (CBO) at the FTE/perovskite interface holds significant potential for enhancing the power conversion efficiency (PCE) of the device. The upward shift in the valance band of HTL promotes recombination and reduces the device performance. The bandgap and electron affinity of RTE highly influence the band alignment at HTL/RTE interface. The NiO/Ag/NiO (NAN) tri-layer RTE provides a better band alignment with HTL, and improves the charge transportation and, hence, the device performance. Moreover, the thickness of the interfacial defect layer at the FTE/perovskite and perovskite/HTL interfaces significantly impacts device performance. In optimizing the perovskite absorber layer, a perovskite bandgap of 1.4 eV shows maximum device performance. Our optimized device shows a remarkable PCE of >27% for both front and rear illumination.

Passive thermoelectric devices that utilize radiative cooling and solar heating have witnessed significant advancements in power generation. However, their applications and promotions are limited due to the low and unsustainable output. In this study, we propose a compact passive thermoelectric device (TED) consisting of a thermoelectric generator (TEG) equipped with a radiative cooler (RCer) and a solar absorber (SAer) for 24-h electricity generation. The RCer is made of a high-scattering porous cellulose film with a thickness of 100 μm. It is coated onto the TEG's sky-facing terminal which serves as the cold end. The SAer is made of an aluminum substrate coated with black paint. It is attached to the opposite TEG terminal which serves as the hot end. By compactly integrating the RCer and SAer, the proposed TED can harvest energy from the space for continuous electric power generation with manageable implementations. Outdoor experiments have shown that during a clear daytime, the maximum temperature difference between the TEG ends reached 7.7 °C, with an average of 2.8 °C. During the nighttime, the maximum temperature difference between TEG ends could reach 1.7 °C, with an average of 0.9 °C. The maximum power outputs during daytime and nighttime are 351.6 mW·m⁻² and 31.0 mW·m⁻², respectively. This study introduces a conceptual design for a compact passive TED and lays the foundation for practical applications in powering outdoor microdevices.

Electrochemical ammonia synthesis is being widely investigated to couple with renewable electricity for future sustainable ammonia production. Protonic ceramic electrochemical cells (PCECs) possess superior energy transfer efficiency and remarkable flexibility to produce high-demand chemicals such as H₂, CH₄, and NH₃ from readily available feedstocks (e.g., H₂O, CO₂, N₂). Despite recent advances that have been established, the research for the high-efficiency PCECs for practical ammonia synthesis continues. In this review, we summarized the recent progress of PCECs for ammonia synthesis. First, we briefly introduce the basic mechanisms and protocols of the ammonia synthesis. Then, we systemically introduce the cell configurations, representative electrolytes and electrodes of PCECs for the ammonia synthesis. We highlight the strategies to tune the ion/electron mobility and the catalytic performance, which are related to the defect structures and redox properties of the electrolyte/electrode, and the opportunities for next-generation ammonia synthesis. Finally, perspectives on ammonia synthesis in PCECs are proposed consering the current challenges.

The study highlights effect of surface modification of SnO₂ photoelectrode by MgO coating on photovoltaic properties of dye-sensitized solar cells (DSSCs). A thin coating of MgO on SnO₂ photoelectrode was prepared using sol-gel-derived dip coating technique. The bare SnO₂ and MgO coated SnO₂ composite photoanodes was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis spectrophotometer. The optical absorption study revealed that the modification in SnO₂ by MgO coating caused an increase in absorption by photoanode in visible region. The solar cell was demonstrated by preparing FTO|SnO₂|Dye|MgO|Electrolyte|Pt coated FTO device structure and tested with current density-voltage (J-V) measurement. The effect of precursor concentration of MgO coating on the performance of DSSCs were investigated. It was found that, optimized coating of MgO for 90 seconds on SnO₂ improved all photovoltaic parameters, resulting in enhancement in efficiency by 42% compared to that of DSSC with bare SnO₂ photoanode. The coating of MgO would have reduced the trap states and suppressed interfacial recombination losses by preventing back electron transfer from the conduction band of the semiconductor to HOMO of dye molecule or redox species.

Electrochemical CO₂ reduction (ECCO₂R) is a viable and promising approach for converting the greenhouse gas carbon dioxide into useful chemicals and fuels. Electrochemical activity and product selectivity are essential for this purpose. The ECCO₂R can lead to the formation of a wide variety of by-products, which is primarily dictated by the nature of electrocatalysts. Surface modification of electrocatalysts with oxide and/or hydroxide moieties can be a simple yet effective strategy to improve activity and selectivity of the ECCO₂R process. This article attempts to review and identify relationship between the surface hydroxylation of electrocatalysts and the product selectivity. Impact of electrocatalyst’s surface modification with oxide/hydroxide on activity, product selectivity, intermediate stability, plausible mechanism and catalyst evolution during the ECCO₂R is highlighted by focusing on select and representative research findings. The review finds that the product selectivity is highly dependent not only on the presence of OH group on the electrocatalysts' surfaces but also the type and distribution of the group. Moreover, the selectivity can be tuned by introducing and controlling the density of surface OH. Future perspectives and challenges are also emphasized.

The scale-up of supercapacitors by electrophoretic deposition (EPD) from coin cell to pouch cell with commercially relevant mass loadings and thicknesses is reported. The use of EPD in electrode fabrication mainly reduces the interfacial resistance and increases the mechanical flexibility of the electrodes. The cycling performance or conversion efficiency can also be improved due to the highly porous EPD coatings. An exemplary investigation of activated carbon (AC) electrodes with an electrolyte comprising of tetraethylammonium tetrafluoroborate in acetonitrile is carried out. According to the general literature, EPD of AC on metal substrates has not performed well for supercapacitor electrodes unless they were thinner and with lower mass loadings than commercial requirements. As a consequence, and to redress this research gap, all the electrodes prepared in this work demonstrate high mass loadings (8 mg cm⁻²) and practical layer thicknesses (125 µm) and contain polyvinylidene fluoride binders with electrically conductive carbon black particles. Research investigations include: (a) impact of EPD of AC onto small (10 cm²) and large areas (50 cm²) of aluminum foil current collectors, (b) scaling-up of coin to pouch cells, and (c) the preparation of electrode coatings on both sides of the current collector for the first time using EPD for pouch cell investigations. Our research learning shows the evidence of practical cell performance, including current loading (40 A g⁻¹), tens of thousands of successive charge and discharge operation (150,000 cycles), power (30 kW kg⁻¹) and energy densities (10 W h kg⁻¹), capacitance (154 F g⁻¹), capacitance retention (80%) and coulombic efficiency (relatively close to 100%). Based upon the success of the pouch cells investigated in this work, further research studies on the use of EPD for preparing energy storage electrodes for commercial cylindrical types of supercapacitors is envisaged.

The development of graphene-based electrodes for application in energy storage and energy harvesting devices represents an important strategy for producing wearable devices with requisites of flexibility and good electrochemical performance. Herein, the use of laser-induced graphene (LIG) has been explored as a simple and efficient method for the production of interdigitated microsupercapacitors (μSCs) and back electrodes for triboelectric nanogenerators (TENGs) active layers by direct production of graphene from Kapton polyimide and by the transference of the pattern to polydimethylsiloxane (a typical tribonegative layer for TENG). An open circuit voltage of 189.7 V, short circuit current of 39.8 μA, and power of 302.5 μW (power density of 20.2 μW/cm²) was observed for the conventional TENG while an areal capacitance of 2.5 mF/cm² with good retention in the energy generation and cyclability in energy storage was observed for the microsupercapacitor. The most relevant aspect to be considered is a single-step method for transference of back-electrode to the Poly(dimethylsiloxane) requiring minimal processing steps for morphology control in the friction layer and self-powered behavior for integration of TENG/microsupercapacitor in a power unit cell.