To drive electronic devices for a long range, the energy density of Li-ion batteries must be further enhanced, and high-energy cathode materials are required. Among the cathode materials, LiCoO2 (LCO) is one of the most promising candidates when charged to higher voltages over 4.3 V. However, high-voltage LCO materials are confronted with severe surface and bulk issues inducing poor cyclic stability. To completely unleash the potential of LCO cathodes, a more comprehensive theoretical understanding of the underlying issues is necessary, along with active exploration of previous modifications. This paper mainly presents the degradation mechanisms of LCO under high voltage, the formation and evolution mechanisms of the cathode electrolyte interface, and the surface engineering strategies employed to enhance the cell performance. By organizing and summarizing these modifications, this work aims to establish associations among common research issues and to suggest future research priorities, thus facilitating the rapid development of high-voltage LCO.
In order to properly utilize the abundant CO2 and water resources, various catalytic materials have been developed to convert them into valuable chemicals as renewable fuels electrochemically or photochemically. Currently, most studies are conducted under mild laboratory conditions, but for some extreme environments, such as Mars and space stations, there is an urgent need to develop new catalysts satisfying such special requirements. Conventional catalytic materials mainly focus on metals and narrow bandgap semiconductor materials, while the research on wide and ultrawide bandgap materials that can inherently withstand extreme conditions has not received enough attention. Given the robust stability and excellent physico-chemical properties of diamond, it can be expected to perform in harsh environments for electrocatalysis or photocatalysis that has not been investigated thoroughly. Here, this review summarizes the catalytic functionality of diamond-based electrodes with various but tunable product selectivity to obtain the varied C1 or C2+ products, and discusses some important factors playing a key role in manipulating the catalytic activity. Moreover, the unique solvation electron effect of diamond gives it a significant advantage in photocatalytic conversions which is also summarized in this mini-review. In the end, prospects are made for the application of diamond-based catalysts under various extreme conditions. The challenges that may be faced in practical applications are also summarized and future break-through directions are proposed at the end.
Photocathodic protection (PCP) is arguably an ideal alternative technology to the conventional electrochemical cathodic protection methods for corrosion mitigation of metallic infrastructure due to its eco-friendliness and low-energy-consumption, but the construction of highlyefficient PCP systems still remains challenging, caused primarily by the lack of driving force to guide the charge flow through the whole PCP photoanodes. Here, we tackle this key issue by equipping the PCP photoanode with ferroelectric single-domain PbTiO3 nanoplates, which can form a directional “macroscopic electric field” throughout the entire photoanode controllable by external polarization. The properly poled PCP photoanode allows the photogenerated electrons and holes to migrate in opposite directions, that is, electrons to the protected metal and holes to the photoanode/electrolyte interface, leading to largely suppressed charge annihilation and consequently a considerable boost in the overall solar energy conversion efficiency of the PCP system. The as-fabricated photoanode can not only supply sufficient photocurrent to 304 stainless steel to initiate cathodic protection, but also shift the metal potential to the corrosion-free range. Our findings provide a viable design strategy for future high-performance PCP systems based on ferroelectric nanomaterials with enhanced charge flow manipulation.
Despite their excellent intrinsic stability, low-dimensional Ruddlesden-Popper (LDRP) perovskites face challenges with low power conversion efficiency (PCE), primarily due to the widen bandgap and limited charge transport caused by the bulky spacer cation. Herein, we introduce formamidinium chloride (FACl) as an additive into (4-FPEA)2MA4Pb5I16 perovskite. On the one hand, the addition of FACl narrows the bandgap through cation exchange between MA+ and FA+, thereby extending the light absorption range and enhancing photocurrent generation. On the other hand, this MA+/FA+ cation exchange decelerates the sublimation of methylammonium chloride and prolongs the crystallization of LDRP perovskite, leading to higher crystallinity and better film quality with a decreased trap-state density. Consequently, this approach led to a remarkable PCE of 20.46% for <n> = 5 LDRP perovskite solar cells (PSCs), ranking among the highest for MA/FA mixed low dimensional PSCs reported to date. Remarkably, our PSCs maintained 90% and 92% of the initial efficiency even after 1300 h at (60 ± 5)°C and (60 ± 5)% relative humidity, respectively. This work promotes the development of LDRP PSCs with excellent efficiency and environmental stability for potential commercial application.
The environmental challenges and growing energy demand have promoted the development of renewable energy, including solar, tidal, and wind. The next-generation electrochemical energy storage (EES), incorporating flow battery (FB) and metal-based battery (MB, Li, Na, Zn, Mg, etc.) received more attention. The flammable electrolytes in nonaqueous batteries have raised serious safety hazards and more unconventional electrolyte systems have been proposed recently. An emerging class of electrolytes, eutectic electrolytes have been reported in many batteries due to the facile preparation, concentrated states, and unique ion transport properties. In FB, eutectic electrolytes can significantly increase the energy density by promoting the molar ratio of redox active materials. In MB, eutectic electrolytes reduce the vapor pressure and toxicity, inhibit metal dendrites growth, and enlarge the electrochemical window. In this review, we summarize the progress status of different eutectic electrolytes on both FBs and MBs. We expect this review can supply the guidance for the application of eutectic electrolytes in EES.
Cobalt phosphides attract broad attention as alternatives to platinum-based materials towards hydrogen evolution reaction (HER). The catalytic performance of cobalt phosphides largely depends on the phase structure, but figuring out the optimal phase towards HER remains challenging due to their diverse stoichiometries. In our work, a series of cobalt phosphide nanoparticles with different phase structures but similar particle sizes (CoP-Co2P, Co2P-Co, Co2P, and CoP) on a porous carbon network (PC) were accurately synthesized. The CoP-Co2P/PC heterostructure demonstrates upgraded HER catalytic activity with a low overpotential of 96.7 and 162.1 mV at 10 mA cm-2 in 1 M KOH and 1 M phosphate-buffered saline solution, respectively, with a long-term (120 h) durability. In addition, the CoP-Co2P/PC exhibits good HER performance in alkaline seawater, with a small overpotential of 111.2 mV at 10 mA cm−2 and a low Tafel slope of 64.2 mV dec−1, as well as promising stability. Density functional theory results show that the Co2P side of the CoP-Co2P/PC heterostructure has the best Gibbs free energy of each step for HER, which contributes to the high HER activity. This study sets the stage for the advancement of high-performance HER electrocatalysts and the implementation of large-scale seawater electrolysis.
The ongoing fourth industrial revolution, also known as “Industry 4.0” is the driving force behind the digitalization of various manufacturing systems by incorporating smart autonomous systems, the Internet of Things (IoT), robotics, and artificial intelligence. In terms of aerospace composites, comprehensive research has been carried out in the past decade or so to manufacture smart and self-sensing fiber-reinforced polymer composites capable of monitoring their own health states. This review focuses on recent developments in smart, self-sensing fiber-reinforced composites incorporating nanomaterial-coated piezoresistive fabric sensors such as carbon nanotubes (CNTs), graphene, and MXene. A comprehensive overview of process monitoring involving the complete resin infusion cycle, such as compaction response, resin flow monitoring, pressure variations within the mold, process-induced defects monitoring, and cure/post-cure monitoring, has been provided. The post-manufacturing structuring health monitoring (SHM) of composites has also been discussed in detail. An overview of the associated challenges of these sensors, such as manufacturability, robustness, conductivity/piezoresistivity calibration, and the effect on structural integrity, is presented. Finally, future insights into the application of these sensors in the physical and cyber domains for smart factories of the future have also been discussed.
We present a one-pot colloidal synthesis method for producing monodisperse multi-metal (Co, Mn, and Fe) spinel nanocrystals (NCs), including nanocubes, nano-octahedra, and concave nanocubes. This study explores the mechanism of morphology control, showcasing the pivotal roles of metal precursors and capping ligands in determining the exposed crystal planes on the NC surface. The cubic spinel NCs, terminated with exclusive {100}-facets, demonstrate superior electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media compared to their octahedral and concave cubic counterparts. Specifically, at 0.85 V, (CoMn)Fe2O4 spinel oxide nanocubes achieve a high mass activity of 23.9 A/g and exhibit excellent stability, highlighting the promising ORR performance associated with {100}-facets of multi-metal spinel oxides over other low-index and high-index facets. Motivated by exploring the correlation between ORR performance and surface atom arrangement (active sites), surface element composition, as well as other factors, this study introduces a prospective approach for shapecontrolled synthesis of advanced spinel oxide NCs. It underscores the significance of catalyst shape control and suggests potential applications as nonprecious metal ORR electrocatalysts.
The escalating accumulation of plastic waste has been developed into a formidable global environmental challenge. Traditional disposal methods such as landfilling and incineration not only exacerbate environmental degradation by releasing harmful chemicals and greenhouse gases, but also squander finite resources that could otherwise be recycled or repurposed. Upcycling is a kind of plastic recycling technology that converts plastic waste into high-value chemicals and helps to avoid resource waste and environmental pollution. Electrocatalytic upcycling emerges as a novel technology distinguished by its mild operational conditions, high transformation efficiency and product selectivity. This review commences with an overview of the recycling and upcycling technology employed in plastic waste management and the respective advantages and inherent limitations are also delineated. The different types of plastic waste upcycled by electrocatalytic strategy are then discussed and the plastic waste transformation process is examined together with the mechanisms underlying the electrocatalytic upcycling. Furthermore, the structure-activity relationships between electrocatalysts and plastic waste upcycling performance are also elucidated. The review aims to furnish readers with a comprehensive understanding of the electrocatalytic techniques for plastic waste upcycling and to provide a guidance for the design of electrocatalysts towards efficient plastic waste transformation.