Organic redox-active molecules (ORAMs) are abundant and diverse, offering significant potential for cost-effective and sustainable energy storage, particularly in aqueous organic flow batteries (AOFBs). However, ensuring the stability of the ORAMs during the charge and discharge process is critical, as side reactions can deactivate them and eliminate their redox activity. Air stability remains a challenge for many ORAMs, complicating their practical use.Recently, a research group led by Prof. LI Xianfeng and Prof. ZHANG Changkun from the Dalian Institute of Chemical Physics (DlCP) of the Chinese Academy of Sciences (CAS) developed novel naphthalene derivatives with active hydroxyls and dimethylamine scaffolds that were stable in air and served as effective catholytes for AOFBs. This study, published in Nature Sustainability, demonstrates that these novel ORAMs can achieve long-term stable cycling even under air-atmosphere conditions.Chemical and electrochemical reaction of the naphthalene derivatives (Image by ZHAO Ziming and ZHANG Changkun)ORAMs are challenged with instability and high cost, particularly when used without inert gas protection. This can lead to irreversible capacity loss and a reduced battery lifespan.In this study, the researchers synthesized active naphthalene derivatives using a scalable approach that combined chemical and in situ electrochemical methods. This approach simplified the purification process and significantly reduced the cost of molecular synthesis.Moreover, the researchers demonstrated specific structure changes in the naphthalene derivatives during the electrochemical process. The as-prepared naphthalene derivatives featured a multisubstituted framework with hydrophilic alkylamine scaffolds, which not only protected against potential side reactions but also improved their solubility in aqueous electrolytes.The 1.5 mol/L naphthalene-based AOFB displayed stable cycling performance for 850 cycles (about 40 days) with a capacity of 50 Ah/L. Remarkably, even with continuous air flow in the catholyte, the naphthalene-based AOFB could run smoothly for approximately 600 cycles (about 22 days) without capacity and efficiency decay. This demonstrated that the naphthalene-based catholyte had excellent air stability.Apilot-scale naphthalene-based flow stack (Image by ZHAO Ziming and ZHANG Changkun)Furthermore, the researchers scaled up the preparation of naphthalene derivatives to the kilogram scale (5 kg per pot). Pilot-scale battery stacks containing these naphthalene derivatives achieved an average system capacity of approximately 330 Ah. They exhibited remarkable cycling stability over 270 cycles (about 27 days), with a capacity retention of 99.95% per cycle."This study is expected to open a new field in the design of air-stable molecular for sustainable and air-stable electrochemical energy storage," said Prof. LI.

The synthesis of molybdenum carbide catalysts typically requires high temperature, leading to inevitable passivation in an oxygen-containing atmosphere. Developing a new route to produce molybdenum carbide at low temperatures is challenging but essential to increase the density of surface active sites.Recently, a research group led by Prof. BAO Xinhe and Prof. FU Qiang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) revealed an in-situ dynamic carbonization method to synthesize molybdenum carbide in reverse water-gas shift (RWGS) reaction. This study was published in Angewandte Chemie International Edition.In-situ carbonization process of the Mo-based catalyst during RWGS reaction for unprecedented high CO formation (Image by DU xiangze)The researchers discovered that introducing intercalated hydrogen into MoO3 to form HxMoOy promoted its reduction, enabling in-situ carburization at 500 ℃ during the RWGS reaction. This carbonization process produced highly active molybdenum carbide, which exhibited enhanced activity in the RWGS reaction.The researchers indicated that both the surface properties of the catalysts and the reaction microenvironment affected the carbonization process. Specifically, a low O/Mo ratio of the catalyst was more favorable to carbonization, while a high CO2 conversion rate, or a high CO partial pressure, further enhanced the carbonization process.Moreover, the researchers demonstrated that carbonization significantly improved CO2 adsorption and activation, thereby enhancing the activity of the RWGS reaction. This in-situ carburization strategy provided insights into the synthesis of metal carbides in a carbon-containing reaction atmosphere."The structural evolution of the catalyst plays an important role during the reaction, which can be used to enhance the catalytic performance by the rational control strategy," said Prof. FU.This work was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the Photon Science Center for Carbon Neutrality.

Glycerol is a key byproduct of biodiesel fabrication, and its production has increased proportionally with the growth of biodiesel production.Glycerol electrooxidation is considered as an innovative strategy due to its low theoretical potential and the elimination of the need for external toxic oxidative agents, pressurized oxygen, and high temperature. Ni-based catalysts featured with abundant supply, low cost, and corrosion resistance were used for glycerol electrooxidation reactions. However, the onset potential was subjected to the high generation potential of NiOOH, which is 1.35 V vs. RHE, leading to inferior electrooxidation activity.Recently, a joint research team led by Prof. WU Zhong-Shuai and Prof. XIAO Jianping from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences has developed a highly active Cu-doped NiCo alloy (Cu-NiCo/NF) catalyst, and constructed an energy-saving nitrate reduction system coupled with glycerol oxidation. This approach has achieved high glycerol electrooxidation activity and selectivity to produce formate at room temperature. This study was published in Angewandte Chemie-International Edition.Schematic illustration of the synthesis of Cu-NiCo/NF and the spontaneous GOR on the Cu-NiCo/NF surface, and changes in glycerol conversions and products yields with electrolysis time for the NO3-RR||GOR flow cell (Image by LI Chenyang and LI Hao)The researchers developed a novel and general high-performance alloy catalyst, Cu-NiCo/NF, for high-yield glycerol electrooxidation. The catalyst, fabricated through one-step electrodeposition, exhibited exceptional glycerol oxidation reaction (GOR) performance, requiring only 1.23 and 1.33 V vs. RHE to achieve 10 and 100 mA cm-2, respectively, while achieving a Faraday efficiency for formate of 93.8%.The researchers identified that the rapid generation of NiIII-OOH and CoIII-OOH as active species were promptly consumed during GOR, confirming the structural stability of the Cu-NiCo/NF catalyst. Besides, Cu doping in NiCo reduced the energy barrier and △G of the C-O coupling process, resulting in superior performance of electrocatalytic GOR.Moreover, the researchers demonstrated that the Cu-NiCo/NF catalyst performed high activity and selectivity for the nitrate reduction reaction (NO3-RR). Using Cu-NiCo/NF as a bifunctional catalyst, the researchers established a NO3-RR||GOR system to produce NH3 and formate simultaneously, requiring only 1.11 and 1.37 V to achieve 10 and 100 mA cm-2, respectively. The system exhibited excellent long-term stability for up to 144 hours, with formic acid remaining the primary product at the anode. When the glycerol conversion rate reached 87.6%, the formation yield was 80.6%."This work not only develops a bifunctional electrocatalyst for GOR and nitrate reduction with high catalytic activity but also provides a new strategy for electrochemical refinery with product upgrades," said Prof. WU.

Accurate prediction of lithium battery lifespan is crucial for the proper functioning of electrical equipment. However, predicting battery lifespan accurately is challenging due to the nonlinearity of capacity degradation and the uncertainty of operating conditions.Recently, Prof. CHEN Zhongwei and Ass. Prof. MAO Zhiyu from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, in collaboration with Prof. FENG Jiangtao from Xi'an Jiaotong University, designed a novel deep learning model, referred to as the Dual Stream-vision Transformer-efficient Self Attention mechanism (DS-ViT-ESA), which overcame the traditional reliance on extensive charging test data.This model provided new insights for real-time battery life prediction and enabled end-to-end evaluation of lithium battery lifespan. Additionally, it is a key component of the team's first-generation Battery Digital Brain core algorithm, known as Power Battery Systems Research Department Digit (PBSRD Digit), which offers solutions for intelligent battery management.Detailed illustration of DS-ViT-ESA model (Image by LIU Yunpeng)The researchers developed the deep learning model using a small amount of charging cycle data. This model employed a vision transformer structure with a dual-stream framework and an efficient self-attention mechanism to capture and integrate hidden features across multiple time scales. As a result, it was able to accurately predict the battery's current cycle life (CCL) and remaining useful life (RUL). With just 15 charging cycle data points, the model achieved RUL and CLL prediction errors of only 5.40% and 4.64%, respectively. Moreover, the model maintained low prediction errors even when tested on charging strategies not included in the training dataset, demonstrating its zero-shot generalization capability.This battery lifespan prediction model was also a crucial component of the first-generation Battery Digital Brain, called PBSRD Digit. By integrating this algorithm, the system's accuracy was significantly improved. Currently, the Battery Digital Brain system served as the core energy management system for large-scale commercial storage and electric vehicles, with the capability to be deployed on both cloud servers and client-side embedded devices."The battery lifespan prediction model effectively balances prediction accuracy with computational cost, thereby increasing the application value of the Battery Digital Brain for lifespan estimation," said Prof. CHEN. "We plan to further optimize the model using techniques such as model distillation and pruning, aiming to enhance robustness and resource utilization of the system," Prof. CHEN added.<!--!doctype-->

Solution-processed semiconductor nanocrystals, also called colloidal quantum dots (QDs), are recognized by the Nobel Prize in chemistry in 2023. As highlighted by the Nobel committee, while the concept of size-dependent quantum effects had been long known to physicists, a sculpture of the theory into real nanodimensional objects remained impossible till the discovery of QDs.The size-dependent colors of QDs are essentially naked-eye, ambient-condition visualization of the quantum size effect. In recent years, researchers across the world have been searching further for fascinating quantum effects or phenomena using the material platform of QDs, such as single-photon emission and quantum coherence manipulation.Floquet states (i.e., the photon-dressed states) are ubiquitously invoked to explain quantum phenomena in relation to coherent interaction between light field and matter. However, direct observation of these Floquet states has been an experimental challenge. For example, only until very recently did researchers report experimental signatures of Floquet-Bloch bands in black phosphorus (a narrow-gap model semiconductor) interacting with mid-infrared pulses by using complex time- and angle-resolved photoemission spectroscopy. In such studies, the samples were almost exclusively housed in low-temperature, high-vacuum environments, and the driving fields were tuned to the infrared, terahertz, or even microwave regions to avoid sample damage.Observation of Floquet states in colloidal nanoplatelets driven by visible pulses (Image by LI Yuxuan)In a study published in Nature Photonics, Prof. WU Kaifeng and his coworkers from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences reported the first direct observation of Floquet states in semiconductors by using all-optical spectroscopy in the visible to near-infrared region under ambient conditions.The idea is to adopt the quasi-two-dimensional colloidal nanoplatelets developed in the past decade, for which the strong, atomically-precise quantum confinement in the thickness dimension results in interband and intersubband transitions in the visible and near-infrared regions, respectively. The levels involved in such transitions naturally form a three-level system. A sub-bandgap visible photon dresses a heavy-hole state (|hh1⟩) to a Floquet state of the same parity as the first quantized electron state (|e1⟩), allowing this Floquet state to be probed by a near-infrared photon through its transition to the second quantized electron state (|e2⟩).Moreover, while the transiently populated Floquet states were often assumed to fade away outside the temporal overlap of pump and probe pulses, they directly observed dephasing of the Floquet state into real population of |e1⟩ in hundreds of femtoseconds. All the experimental observations in this study are substantiated by quantum mechanical simulations."Not only does this study provide an all-optical direct observation of Floquet states in semiconductor materials, but it also uncovers the rich spectral and dynamic physics of Floquet states that can be harnessed to dynamically control the optical responses and coherent evolution in condensed-matter systems", said Prof. WU.Moreover, since the current demonstration is attained for colloidal materials under ambient conditions, it will expand the reach of Floquet engineering, which currently focuses on tailoring the quantum and topological properties of solid-state materials, to coherently controlling surface/interfacial chemical reactions through nonresonant light field.

Stress-induced cracks often lead to catastrophic failure of materials. For membranes, stress loads concomitant with thermal and mechanical risks during separation will gradually produce cracks, which weaken the stability and reliability of membranes in long-term separation processes.Recently, a research group led by Prof. YANG Weishen and Prof. BAN Yujie from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) proposed adaptive healing of stress-induced dynamic cracks in a metal-organic framework membrane using nanoparticles.This study was published in Science Advances on 31 July.Shapes of adaptive healing zones in a MOF membrane (A), the separation durability of the membrane after adaptive healing (B) (Image by BAN Yujie and WANG Yuecheng)Traditional post crack-healing technologies have been widely applied. However, due to the spatiotemporal mismatch between crack formation and crack healing, they lack of point-by-point healing accuracy and result in a large healing zone, thus leading to increased membrane thickness and mass transfer resistance.In this study, the research team proposed adaptive healing of stress-induced dynamic cracks (AHSDC) in membranes using nanoparticles.The researchers indicated that the core was to create spatiotemporal harmony between generation and healing of cracks. Therefore, AHSDC leveraged risk factors to overcome the membrane's tolerance limits and made stress-induced dynamic cracks fully exposed prior to separation. At the same time, AHSDC employed in situ formed nanoparticles in the same chemical environment to immediately fill crack gaps once cracks formed in the membrane.Furthermore, the researchers proved that AHSDC could function with point-by-point accuracy and form adaptive healing zones with the ability of self-selecting their shapes according to peculiarities of cracks."Our membrane after AHSDC retained satisfactory separation performances for azeotropic mixtures with energy consumption saved by approximately 85%, such as the ethanol-water system", said Prof. YANG."The separation durability was improved by at least two orders of magnitude," said Prof. BAN.