Advanced Energy and Sustainability Research最新文献

Hydrogen as a potential future energy source provides a number of benefits in terms of sustainability, high energy density, and zero emissions. The production of hydrogen via water splitting is regarded as the cleanest and sustainable process. In contrast, fossil fuel combustion causes significant environmental problems through the production and release of secondary gases such as NO_x, SO₂, and CO₂. It is vital to focus on reducing these harmful gases. CO₂, a major pollutant produced by the combustion of fossil fuels and various human activities, plays a central role in the greenhouse effect and contributes to global warming. It is therefore imperative to actively eliminate and mitigate CO₂ levels to preserve the global environment. MXenes and MXene-based catalysts exhibit both outstanding hydrogen evolution reaction (HER) performance and CO₂ reduction. In this review, recent progress is systematically examined and discussed in the preparation and utilization of MXenes as catalysts for HER and carbon dioxide reduction reaction (CO₂RR). The discussion begins with a concise overview of the fabrication and characteristics of MXenes, followed by a comprehensive exploration of their efficacy as catalysts for HER and CO₂RR.

The iron-based pyrophosphate Na₂FeP₂O₇ (NFP) is considered as one of the most promising cathodes for sodium-ion batteries (SIBs) due to its low-cost and superior structure stability, yet it usually suffers from poor intrinsic electronic conductivity. Herein, a two-step carbon-coating technique has been developed to synthesize high-performance NFP@C cathode materials by controlling the NFP particle size and the coating layer uniformity. The first step of in-situ carbon coating greatly restrains the excessive growth of NFP crystals with a shortened Na-ion diffusion path. Meantime, the extra secondary carbon-coating is adopted to repair some exposed areas, guaranteeing the full coverage of NFP particles for rapid electronic transfer. As a consequence, the as-obtained NFP@C cathode delivers a high discharge capacity of 95.2 mAh g⁻¹ at 0.1 C (theoretical value: 97 mAh g⁻¹) and with high-rate capability (75.2 mAh g⁻¹ at 5 C) within 2.0–4.0 V. A capacity retention of 95.3% can be achieved even after 500 cycles at 5 C in coin-type cells. Such superior electrochemical performances are expected to quickly promote the applications of NFP in SIBs.

Silicon is the most diffused material in the industry; thus, considering its high capacity for energy storage, silicon-based materials are well studied as battery anodes and supercapacitors. Si nanowires (NWs) emerge due to the high surface to volume ratio, its compatibility with a wafer processing typical of microelectronics, and are studied as anodes for lithium batteries as well as coupled with other materials for supercapacitor application. In this article, the synthesis and application are reported as a lithium anode of 2D fractal arrays of ultrathin Si NWs obtained by a thin-film metal-assisted chemical etching (MACE). These Si NWs exhibit a density of about 10¹² NWs cm⁻², maximizing the surface to volume ratio compared to silver-salts MACE and other NW fabrication approaches. By using 2.7 μm long NWs, a pseudo-capacitor behavior with a specific capacitance of about 274.2 μF cm⁻² at a scan rate of 50 mV s⁻¹ is obtained. This specific capacitance is two orders of magnitude higher than the one obtained in the same condition by using NWs synthesized by silver-salt MACE. In this result, the route is opened toward the application of these fractal arrays of ultrathin Si NWs as substrate for supercapacitors with improved efficiency.

Water scarcity and sanitation pose a critical global challenge worsened by population growth and the finite nature of freshwater resources. Despite the United Nations’ Sustainable Development Goal 6 (SDG6) advocating for universal water and sanitation access, progress remains insufficient. Presently, approximately 50% of generated wastewater is released into the environment without adequate treatment, emphasizing the urgent need to address this issue. This article examines the socio-economic and technical aspects of both centralized and decentralized wastewater treatment systems (DWTS) and assesses the environmental impact, spatial footprint, and energy usage across treatment technologies. An economic analysis underscores the cost advantages of DWTS, especially in sparsely populated regions. With modular designs, DWTS not only provides environmental and economic advantages but also enables water reuse. The research concludes that adopting DWTS is crucial in achieving SDG6 targets and ensuring universal access to safe sanitation, especially in low-density and newly developed areas. This thorough investigation of wastewater management contributes to the ongoing dialogue on sustainable solutions amidst escalating global challenges of water scarcity and sanitation.

Sustainable Electrical Component

In article number 2300298, Yuya Ishii and co-workers disclose various charge properties of a mat of as-electrospun submicrofibers comprising a sustainable polymer of poly(L-lactic acid). Moreover, an advanced numerical model of the output charge is proposed. Additionally, the fiber mat is applied to a self-power-generative touch sensor and mask-type acoustic sensor using mostly sustainable materials. This study promotes a deeper understanding of the charged electrospun fiber mats and paves the way for the development of their sustainable electrical applications.

Recycled Polymers

Polystyrene packing foam ends up in landfill en masse. In article number 2300259, Andris Šutka, Peter C. Sherrell, and co-workers have developed a recycling process which introduces mechanical-to-electrical conversion functionality into polystyrene. The process creates fibrous ‘laminates’ with internal triboelectrification. These laminates show equivalent performance to state-of-the-art piezoelectric materials, paving the way for upcycling of waste polymers into energy harvesters, sensors, and functional systems and devices.

Lithium dendrites are among the most significant threats associated with the practical application of lithium metal anode in lithium batteries. Lithium dendrites are caused by the slow Li-ion diffusivity in the bulk lithium, which results in a non-uniform electric field-cum-uneven Li plating/stripping at the electrode/electrolyte interface over prolonged cycling. Herein, a facile chemical reduction method is utilized to construct a Li-ion diffusive Li–Sn protective layer on the electrolyte-exposed surface of lithium metal to overcome the aforementioned challenge. A systematic study on the SnCl₄ precursor concentration variation demonstrated that 25 mM SnCl₄ concentration is the most effective and displays a cumulative areal capacity beyond 700 mAh cm⁻² at 1 mA cm⁻² for 1 h. Moreover, it exhibits superior cumulative capacities than bare Li metal at higher current densities of 2 and 3 mA cm⁻². In situ optical microscopy reveals more uniform lithium deposition on the Li–Sn-modified electrode, while mossy and dendritic lithium growth is observed on the bare lithium electrode. Full cells fabricated with Li–Sn modified anode and NMC532 cathode exhibited 83% capacity retention after 150 cycles, outperforming bare Li-containing cells, which shows a catastrophic decay post 100 cycles, illustrating the propensity for safer Li metal batteries with Li–Sn modified anode.

This study examines the need for bismuth as a catalyst for the Cr²⁺/Cr³⁺ redox couple in an iron–chrome redox flow battery (ICRFB) using 1) open-circuit voltage (OCV) periods to understand the impact of bismuth and the mechanism of hydrogen production with and without electrolyte flow, and 2) charge/discharge cycles to evaluate how bismuth influences ICRFB performance. The OCV study finds that the capacity decay in the ICRFB cycling is not solely due to the hydrogen evolution reaction, suggesting an alternative oxidation reaction is involved, likely catalyzed by metallic carbides like bismuth carbide. Both the OCV and the ICRFB confirm that the presence of bismuth negatively influences the battery performance due to increased H₂ production. Further research is ongoing to validate the decay mechanism and confirm these results on a larger scale.

Li/Mn-rich layered oxide (LMR) cathode active materials promise exceptionally high practical specific discharge capacity (>250 mAh g⁻¹) as a result of both conventional cationic and anionic oxygen redox. The latter requires electrochemical activation at high cathode potential (>4.5 V vs Li|Li⁺), though it is accompanied by capacity and voltage fade in the course of continuous release of lattice oxygen, layered-to-spinel phase transformation, redox couple shift, as well as transition metal dissolution, whereas the latter is particularly detrimental for graphite-based anodes due to electrode crosstalk. Herein, the degradation is investigated in LMR || graphite full cells by systematically varying the voltage windows, analyzing electrochemical data and changes at the anode surface. Based on this, the optimal operational voltage window, i.e., upper and lower cutoff voltage (UCV and LCV), is elaborated to finally solve the dilemma of decent cycle life (at high UCVs) and insufficient LMR activation/capacity (at low UCV) and is shown to be superior via distinguishing between formation and postformation cycles of 4.5 and 4.3 V, respectively.

Triboelectric nanogenerators (TENGs) are promising self-powering supplies for various intelligent sensing and monitoring devices, especially because they can harvest electric energy from low frequency and small-scale mechanical motions. Despite the fact that contact-separation mode TENGs with smaller contact areas harvest higher electrical outputs due to fringing effect, the impact of fringing effect on TENGs’ electrical outputs is rarely investigated quantitatively. Herein, in this study, the influence of fringing effect on the electrical outputs of contact-separation mode TENGs by introducing discontinuity on the tribo-negative side manually is investigated. In the results, it is revealed that the TENGs with more discontinuities show higher overall electric performance. Compared to pristine TENGs, the TENGs with discontinuity increased significantly, improving the surface charge by 50% and the power density by 114% when cross discontinuities are applied. However, one should generate discontinuities on tribo-negative side of TENGs using ceramic blade instead of metal blade within a positive-ion atmosphere due to the neutralization through the electrically conductive metal blade. The computational simulation validates that the TENGs with discontinuities obtain higher electrical outputs, and further investigates the effect of discontinuity gap size and array distance on TENGs performance. In this study, a promising method is provided for the future design of TENGs using discontinuous structures.