{"title":"Microscale Bipolar Interfaces for High-Power Fuel Cells","authors":"Jianping Chen, Kritika Sharma, Zhongyang Wang, Shrihari Sankarasubramanian, Vijay Ramani","doi":"10.1021/accountsmr.5c00039","DOIUrl":"https://doi.org/10.1021/accountsmr.5c00039","url":null,"abstract":"Electrochemical devices are typically designed for operation over a narrow pH range and are constrained in the choice of catalysts and operating potentials by the pH environment of the electrodes. This is the result of a heretofore lack of a viable strategy to maintain pH gradients between the electrodes over practically significant time durations with only a minimal impact on the device performance. While bipolar interfaces are well-known, they typically result in high junction potential losses that make them impractical in real-life systems. We have demonstrated a way to overcome this long-standing challenge using our tailor-made, microscale bipolar interfaces, which allows the use of acidic electrolytes at one electrode and alkaline electrolytes at the other, without mixing over time. This allows for a much broader selection of fuel and oxidant stream catalysts (moving away from platinum group metals) and electrolytes to be used. Low-temperature aqueous fuel cells have been constrained in their operating voltage to ca. 1.2–1.5 V (as a function of fuel and oxidant combination) by the water splitting side reactions (hydrogen evolution reaction (HER) and oxygen evolution reaction (OER)). This relatively low cell voltage translates to larger stack volumes for a desired power output and poor specific power output. By employing our pH-gradient enabled microscale bipolar interfaces (PMBIs) we have demonstrated aqueous direct borohydride fuel cells (DBFC) that provide a 2.4 times higher power density at 1.5 V, compared to state-of-the-art polymer electrolyte membrane fuel cells (PEMFCs) that typically operate at 0.75 V. This Account traces the >10 year development of PMBIs. We detail the development of a recessed planar electrode that provided experimental evidence that the PMBI was able to maintain a sharp local pH gradient (0.82 pH units nm<sup>–1</sup> on average) at the electrocatalytic reaction sites. We go on to trace the evolution of a series of highly selective anion exchange ionomer (AEIs) that enabled ever higher intercell pH gradients and culminated in the demonstration of the highest power operation of a bipolar DBFC reported in the literature. PMBIs have also enabled recent developments in high power bipolar direct methanol- and direct ethanol fuel cells (DMFC and DEFC) employing hydrogen peroxide oxidants. PMBI-based DMFC and DEFC achieved open-circuit voltages near their theoretical maxima (∼1.7 V and ∼1.65 V, respectively). Emerging strategies such as molecular modeling-guided ionomer design, self-healing bipolar interfaces, and optoelectronic coupling represent promising future directions to further enhance PMBI stability, ion transport efficiency, and expand their practical applicability in high-performance electrochemical energy conversion devices.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu-Wu Zhong, Meng-Jia Sun, Chun-Yun Ding, Zhong-Qiu Li, Jiannian Yao
{"title":"Brightening the Microcrystals of Polyazine Iridium and Ruthenium Complexes via Light-Harvesting Energy Transfer","authors":"Yu-Wu Zhong, Meng-Jia Sun, Chun-Yun Ding, Zhong-Qiu Li, Jiannian Yao","doi":"10.1021/accountsmr.5c00052","DOIUrl":"https://doi.org/10.1021/accountsmr.5c00052","url":null,"abstract":"Luminescent nano/micro molecular crystals with well-defined shapes and morphologies have exhibited great potential for various photonic applications. The molecular orientation and packing greatly influence the optical and electronic characters of the crystals. Noncovalent intermolecular interactions can not only determine the growth direction but also induce the formation of polymorphs, bringing more possibilities for the property optimization and functional applications. Besides, light-harvesting energy transfer (LHEnT) is a vital process in natural photosynthesis, the mimic of which provides a simple and practical means for solar energy conversion and the preparation of luminescent materials. With an energy donor and acceptor pair with suitable energy levels and similar molecular size and solubility, it is convenient to fabricate LHEnT molecular crystals with tunable optoelectronic and emission properties by dispersing acceptors into the donor lattices.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stephan Müssig, Andreas Wolf, Tero Kämäräinen, Karl Mandel
{"title":"Information-Providing Magnetic Supraparticles: Particle Designs to Record Environmental Stimuli with Readout by Magnetic Particle Spectroscopy","authors":"Stephan Müssig, Andreas Wolf, Tero Kämäräinen, Karl Mandel","doi":"10.1021/accountsmr.5c00027","DOIUrl":"https://doi.org/10.1021/accountsmr.5c00027","url":null,"abstract":"The ability to gather information about materials and products, such as their origin, physicochemical properties or history of experienced environmental stimuli, is valuable for quality control, predictive maintenance, delivery tracking, recycling, and more. Integrating additives capable of recording and storing information into materials offers a flexible approach to create “materials intelligence”. Common strategies utilize luminescent markers or DNA sequences that enable object identification and environmental impact monitoring.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Film-Depth-Dependent Light Absorption Spectroscopy of Organic Thin Films","authors":"Laju Bu, Xianqiang Xie, Zichao Shen, Guanghao Lu","doi":"10.1021/accountsmr.5c00059","DOIUrl":"https://doi.org/10.1021/accountsmr.5c00059","url":null,"abstract":"Organic thin films, with thickness ranging from tens to hundreds of nanometers, are foundational to organic electronic devices. Yet, vertical phase separation during film deposition and postprocessing, along with the corresponding variations in crystallinity and photoelectric properties along the film-depth direction, critically influences device performance. Traditional characterization methods, such as cross-sectional electron microscopy, neutron reflectivity, or incremental etching coupled with mass spectrometry, suffer from key limitations: sample-destructive analysis, high-cost or inaccessible instrument, or an inability to directly probe depth-dependent optoelectronic behaviors inside the film. These shortcomings hinder the optimal design of high-performance devices. To overcome these challenges, we developed film-depth-dependent light absorption spectroscopy (FLAS), an innovative and accessible technique combining soft plasma etching with UV–vis spectroscopy. FLAS achieves ∼1 nm depth resolution of vertical phase separation, enables seminondestructive profiling of vertical properties, and directly correlates structural insights with device optimization. Over the past decade, FLAS has been widely applied for the depth-dependent analysis of organic films, and its effectiveness in elucidating the relationship between favorable film structure and high device performance has been validated. In this Account, we focus on the mechanisms and device applications of FLAS, aiming to enhance the understanding of vertical variations in organic films and to advance the fabrication of high-performance organic electronic devices. We begin by discussing the challenges associated with characterizing vertical phase separation and other depth-dependent variations in organic films, followed by the introduction of FLAS as an effective solution. We briefly highlight its advantages over conventional analytical techniques. Subsequently, we outline the principles of FLAS, including the Beer–Lambert law, which relates film absorbance to the content of different components, as well as the qualitative and quantitative relationships between depth-dependent absorption spectra and other depth-dependent variables including composition, crystallinity, optical and electrical variations. Elementary mathematical physics approaches, such as the least-squares method and the transfer matrix method (TMM), are employed to simulate film-depth-dependent composition and photoelectric field distribution, respectively. This is followed by a brief introduction to the supporting technique of surface-selective etching using low-pressure oxygen plasma, which enables the removal of surface layers without damage to the underlying sublayers. We then summarize several alternative depth-resolved analytical methods derived in the development of FLAS, such as film-depth-dependent light reflection and infrared spectroscopy. Next, the applications of FLAS in organic electronics, particularly in fiel","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rui Zhang*, Mengxue Du, Katalee Jariyavidyanont, René Androsch*, Evgeny Zhuravlev and Christoph Schick*,
{"title":"","authors":"Rui Zhang*, Mengxue Du, Katalee Jariyavidyanont, René Androsch*, Evgeny Zhuravlev and Christoph Schick*, ","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"6 5","pages":"XXX-XXX XXX-XXX"},"PeriodicalIF":14.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/accountsmr.5c00031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144447727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yaoyuan Zhang*, Yi Dai, Hansheng Li, Guiyuan Jiang* and Evgenii V. Kondratenko*,
{"title":"","authors":"Yaoyuan Zhang*, Yi Dai, Hansheng Li, Guiyuan Jiang* and Evgenii V. Kondratenko*, ","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"6 5","pages":"XXX-XXX XXX-XXX"},"PeriodicalIF":14.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/accountsmr.4c00395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144447720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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