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A strongly coupled multisite anode electrocatalyst with cluster-scale ruthenium-tungsten oxide (Ru-WOx) interface is developed for alkaline anion exchange membrane fuel cells (AEMFCs), which could simultaneously achieve high coverage of hydroxyl (OHad) and hydrogen (Had) at Ru and WOx domains, respectively. The AEMFC delivers a high peak power density of 1.36 W cm−2 with a low anode catalyst loading of 0.05 mgRu cm−2 and outstanding durability.

Abstract

Ruthenium (Ru) is a more cost-effective alternative to platinum anode catalysts for alkaline anion-exchange membrane fuel cells (AEMFCs), but suffers from severe competitive adsorption of hydrogen (Had) and hydroxyl (OHad). To address this concern, a strongly coupled multisite electrocatalyst with highly active cluster-scale ruthenium-tungsten oxide (Ru-WOx) interface, which could eliminate the competitive adsorption phenomenon and achieve high coverage of OHad and Had at Ru and WOx domains, respectively, is designed. The experimental and theoretical results demonstrate that WOx domain functions as a proton sponge to perpetually accommodate the activated hydrogen species that spillover from the adjacent Ru domain, and the resulting WO-Had species are readily coupled with Ru-OHad at the heterointerface to finish the hydrogen oxidation reaction with faster kinetics via the thermodynamically favorable Tafel-Volmer mechanism. The AEMFC delivers a high peak power density of 1.36 W cm−2 with a low anode catalyst loading of 0.05 mgRu cm−2 and outstanding durability (negligible voltage decay over 80-h operation at 500 mA cm−2). This work offers completely new insights into understanding the alkaline HOR mechanism and designing advanced anode catalysts for AEMFCs.

The heart organoid model exhibits the acidic microenvironment characteristic of myocardial infarction, which emerges as a pivotal force propelling the movement of micro-robots. These micro-robots, administered through microneedles, can penetrate deep into the tissue, effectively delivering therapeutic payloads to facilitate heart repair.

Abstract

Post-myocardial infarction (MI), the rapid decrease in pH triggers myocardial cell acidosis, which compromises the therapeutic efficacy of exosomes in MI. The groundbreaking research in the human cardiac organoid MI model suggests that exosomes, when paired with pH adjustment, dramatically reduce cardiomyocyte mortality while maintaining their proliferative potential, underscoring the importance of pH regulation in myocardial preservation. Micro-robot mounted micro-needle (MN) patch is thus proposed, targeting MI-acidic microenvironmet, to deliver exosomes into deep injured tissue. Upon injection, the patch base releases VEGF-laden nanoparticles adhering to the infarcted myocardium. The smart patch is found not only 3D reconstructs the vascular network in MI regions but also effectively saves cardiomyocytes in rats. Furthermore, the minimally invasive delivery of MN patches are also verified to hearts of rabbits and pigs via thoracoscopic surgery underscores. These findings suggest that precise regulation of the microenvironment is a key to improving treatment outcomes.

This study proposes tribenzyl organic cation carried multidentate X-type Lewis soft base to enhance adhesion and passivate defects simultaneously, aiming to achieve foldable and efficient perovskite nanocrystal-based light-emitting diodes. The resulting pure red F-PeLEDs exhibit a recorded high EQE of 16.2% and robust mechanical properties to endure 5000 folding cycles with small radius of 1 mm.

Abstract

Lead-halide perovskite nanocrystals (PNCs) exhibit significant potential for advancing foldable perovskite light-emitting diodes (F-PLEDs) due to their discrete crystalline morphology, bright emission across an extensive color gamut, and remarkable color purity; however, their progression remains in the early stages with the concerns of inadequate performance and mechanical instability. This study proposes a ligand strategy employing tribenzyl organic cation (tribenzylamine, TBA) carried multidentate X-type Lewis soft base (sodium acid pyrophosphate, SAPP) to address the challenges above simultaneously. Specifically, the use of multibranched aromatic ligands considerably improved the adhesion force between PNCs and adjacent layers, enhancing mechanical stability during folding, while the control sample shows deleterious cracks. Additionally, TBA-SAPP ligands effectively eliminate the defects in PNC film, yielding exceptional photoluminescence properties with a near-unity quantum yield. Consequently, the multifunctional ligands improved F-PLEDs to achieve a record-high external quantum efficiency (EQE) of 16.2% compared to the previously reported pure-red flexible PLEDs and display substantially improved spectral and operational stability. Equally important, these devices demonstrate robust mechanical properties, enduring a small folding radius of 1 mm for 5000 cycles. This ligand strategy is anticipated to inspire relevant research in PNCs and promote the realization of highly efficient and mechanically stable F-PLEDs.

The origin of oxygen framework stability is studied by integrating high covalent element Mo into the bulk and surface of ultra-high nickel cathode materials through a one-step method. Mo with strong covalency can suppress Li/Ni antisite defects and reduce Li-O-Li configurations, thus suppressing irreversible phase transition and stabilizing the oxygen framework structure at high voltage.

Abstract

Ultra-high nickel layered oxides are recognized as promising cathode candidates for high-energy-density lithium-ion batteries due to their enhanced overall capacity and elevated operating voltage. However, the interlayer sliding of transition metal-oxygen octahedra (TMO6) and the instability of lattice oxygen at high voltages for ultra-high nickel oxide cathodes pose significant challenges to their development. Herein, the origin of oxygen framework stability is investigated by incorporating high-covalent element Mo in both bulk and surface using a one-step integrated method for ultra-high nickel cathode material LiNi0.92Co0.08O2. It is revealed that apart from the isolation and protection effect of the Mo-enriched surface layer, the suppression of Li/Ni antisite defects by Mo6+ with strong covalency in the bulk plays a critical role in reducing the configurations of the activated anionic redox reaction and stabilizing the lattice oxygen and oxygen framework structure. Benefiting from this, the reversibility of anionic redox reaction and the stability of oxygen framework is significantly enhanced, enabling more oxidized oxygen to exist in the form of oxygen dimer ions O2n−$O_2^{n - }$ rather than being lost as gaseous O2. Consequently, the modified ultra-high nickel material demonstrates improved diffusion kinetics and optimized electrochemical performance at high voltage.

Acid etching assisted direct upcycling strategy that selectively removals rock-salt phases on the surface of highly degraded LiNi0.5Co0.2Mn0.3O2 and dissociating polycrystalline structure to single crystals simultaneously, facilitating direct repair of its composition and structure via simple solid-state sintering. The regenerated LiNi0.5Co0.2Mn0.3O2 exhibits comparable capacity and more excellent electrochemical stability to commercialized ones.

Abstract

Direct recycling of cathode materials has attracted phenomenal attention due to its economic and eco-friendly advantages. However, existing direct recycling technologies are difficult to apply to highly degraded layered materials as the accumulation of thick rock-salt phases on their surfaces not only blocks lithiation channels but also is thermodynamically difficult to transform into layered phases. Here, a surface engineering-assisted direct upcycling strategy that reactivates the lithium diffusion channels at the highly degraded cathode surfaces using acid etching explored. Acid can selectively remove the electrochemically inert rock-salt phases on the surface while simultaneously dissociating the degraded polycrystalline structure to single crystals, thereby reducing the thermodynamic barrier of the relithiation process and enhancing the stability of the regenerated cathode. This strategy can restore the capacity of highly degraded LiNi0.5Co0.2Mn0.3O2 from 59.7 to 165.4 mAh g−1, comparable to that of commercialized ones. The regenerated cathode also exhibits excellent electrochemical stability with a capacity retention of 80.1% at 1 C after 500 cycles within 3.0–4.2 V (vs graphite) in pouch-type full cells. In addition, the generality of this strategy has also been validated on Ni-rich layered materials and LiCoO2. This work presents a promising approach for direct recycling of highly degraded cathode materials.

A novel 3D printing method enables the fabrication of materials with precisely controlled mechanical properties at nanoscale resolution. A volume-conserving photoresist combined with the free and open-source software, OpenScribe, achieves mechanical transitions over 770 nanometers - representing a 130-fold improvement over existing approaches. This advancement enables the creation of complex materials with unprecedented control over local elasticity.

Abstract

Fabrication methods that synthesize materials with higher precision and complexity at ever smaller scales are rapidly developing. Despite such advances, generating complex 3D materials with controlled mechanical properties at the nanoscale remains challenging. Exerting precise control over mechanical properties at the nanoscale would enable material strengths near theoretical maxima, and the replication of natural structures with hitherto unattainable strength-to-weight ratios. Here, a method for fabricating materials with nanovoxelated elastic moduli by employing a volume-conserving photoresist composed of a copolymer hydrogel, along with OpenScribe, an open-source software that enables the precise programming of material mechanics, is presented. Combining these, a material composed of periodic unit cells featuring heteromechanically tessellated soft-stiff structures, achieving a mechanical transition over an order-of-magnitude change in elastic modulus within 770 nm, a 130-fold improvement on previous reports, is demonstrated. This work critically advances material design and opens new avenues for fabricating materials with specifically tailored properties and functionalities through unparalleled control over nanoscale mechanics.

A novel non-fullerene acceptor, BFDO-4F, is integrated into organic photodetectors (OPDs) to enable electron trapping. The resulting devices exhibit dual-mode functionality, with bias-switchable operation between photovoltaic (PV) and photomultiplication (PM) modes. An on-chip module is demonstrated, where the PV section supplies bias for the PM section achieving self-powered amplifier-free system, highlighting the potential for multifunctional OPDs in advanced optoelectronic applications.

Abstract

Photomultiplication-type organic photodetectors (PM-OPDs) provide for signal amplification, ideal for detecting faint light, and simplifying detection systems. However, current designs often suffer from slow response speed and elevated dark current. Conversely, photovoltaic-type organic photodetectors (PV-OPDs) provide fast response and high specific detectivity (D *) but have limited photoresponse. This study presents the synthesis and incorporation of a non-fullerene acceptor, BFDO-4F, into the active layer to introduce trap states for capturing photogenerated electrons. The resulting device exhibits dual-mode characteristic and is bias-switchable between PV and PM-modes. In PV-mode, the OPDs achieve high D * of 1.92 × 10¹2 Jones and a response time of 2.83/4.43 µs. In PM-mode, the OPDs exhibit exceptional external quantum efficiency (EQE) up to 3484% and a D * of up to 1.13 × 10¹2 Jones. An on-chip self-powered module with PV-mode pixels driving a PM-mode pixel is demonstrated, yielding a photocurrent approximately five times higher than the reference device. This approach paves the way for developing multifunctional bias-switchable dual-mode on-chip OPDs, suitable for various applications.

Monotone arrays and a multidimensional Ramsey Theorem

A foundational result in Ramsey theory appears in a paper of Erdős and Szekeres from 1935: any sequence of n^2 +1 distinct real numbers contains either an increasing or decreasing subsequence of length n+1. This simple result was one of the starting seeds for the development of Ramsey theory. We discuss a generalisation of the Erdős-Szekeres theorem to monotone arrays. We will show how to obtain improvements on a theorem proved by Fishburn and Graham 30 years ago thus confirming a conjecture posed by Bucic, Sudakov, and Tran. More precisely, we will show that a doubly exponential upper bound holds in all dimensions. Finally, we will see how this is intimately connected to a generalisation of Ramsey Theorem on the cartesian product of cliques. Joint work with Antonio Girao and Alex Scott.

• Speaker: Gal Kronenberg (Oxford)
• Thursday 13 March 2025, 14:30-15:30
• Venue: MR12.
• Series: Combinatorics Seminar; organiser: ibl10.

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This study constructs a unified supercapacitor database comprising hundreds of MOF electrodes based on constant-potential molecular simulation. The relationships between porous structures and electrochemical performance are thoroughly examined through interpretable machine learning techniques, with molecular insights by analyzing in-pore electrode-ion coordination and ion diffusion. These findings pave the way for the design and optimization of advanced electrode materials.

Abstract

The development of supercapacitors is impeded by the unclear relationships between nanoporous electrode structures and electrochemical performance, primarily due to challenges in decoupling the complex interdependencies of various structural descriptors. While machine learning (ML) techniques offer a promising solution, their application is hindered by the lack of large, unified databases. Herein, constant-potential molecular simulation is used to construct a unified supercapacitor database with hundreds of metal–organic framework (MOF) electrodes. Leveraging this database, well-trained decision-tree-based ML models achieve fast, accurate, and interpretable predictions of capacitance and charging rate, experimentally validated by a representative case. SHAP analyses reveal that specific surface area (SSA) governs gravimetric capacitance while pore size effects are minimal, attributed to the strong dependence of electrode-ion coordination on SSA rather than pore size. SSA and porosity, respectively, dominate volumetric capacitance in 1D-pore and 3D-pore MOFs, pinnacling the indispensable effects of pore dimensionality. Meanwhile, porosity is found to be the most decisive factor in the charging rate for both 1D-pore and 3D-pore MOFs. Especially for 3D-pore MOFs, an exponential increase in porosity is observed in both ionic conductance and in-pore ion diffusion coefficient, ascribed to loosened ion packing. These findings provide profound insights for the design of high-performance supercapacitor electrodes.

Nature Energy, Published online: 07 March 2025; doi:10.1038/s41560-025-01734-8

Thermal stability in high-nickel cathodes has been a long-standing concern due to the lack of standardized assessments. Now, research identifies key factors that trigger thermal runaway and introduces a thermal stability index to help guide the development of safer cathodes.

Nature Energy, Published online: 07 March 2025; doi:10.1038/s41560-025-01731-x

High-nickel oxide cathodes are important for automotive lithium batteries but face thermal instability challenges. This study analyses a range of materials, quantifying how the cathode chemistry, nickel content, morphology and state of charge dictate the stability, and proposes a thermal stability index.

Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02165-2

The number and performance of p-type two-dimensional (2D) semiconductors has been limited. Now, non-layered 2D β-Bi2O3 single crystals are synthesized on a SiO2/Si substrate using a vapour–liquid–solid–solid growth method. Field-effect transistors based on 2D β-Bi2O3 crystals exhibit high hole mobility, on/off current ratio and air stability.

Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02171-4

A simple method combining thermal activation and electric fields is demonstrated to efficiently generate ordered vacancies in bulk metal oxides, which can be used for broad applications.

Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02141-w

High-quality, non-layered 2D β-Bi2O3 crystals are grown using a vapour–liquid–solid–solid growth technique. These crystals demonstrate promising properties for p-channel field-effect transistors.

Nature Materials, Published online: 07 March 2025; doi:10.1038/s41563-025-02146-5

Mechanical stiffness and self-healing properties are difficult to combine in synthetic hydrogels. Using polymer entanglements in co-planar nanoconfinement, stiff and self-healing hydrogels are fabricated, with applications in biology and engineering.

Beyond the Standard Model of particle physics: a maths-driven journey to the unknown

Our current understanding of the elementary building blocks of Nature, encapsulated by the Standard Model (SM) of particle physics, is one of the most successful theory constructions of the past century, yet it is necessarily incomplete. Several experimental observations, such as the presence of Dark Matter and the matter-antimatter asymmetry of the Universe, are currently unexplained by the model. In my talk I will discuss how the uncharted territory beyond the Standard Model can be explored and how Maths can be a precious compass to guide us in the fascinating quest for the unknown.

This talk will be free for all, including non-members.

• Speaker: Prof Maria Ubiali
• Tuesday 18 March 2025, 18:00-19:30
• Venue: Pfizer Lecture Theatre, Department of Chemistry, Lensfield Road.
• Series: SciSoc – Cambridge University Scientific Society; organiser: Zhang Xianghao Jeffrey.

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Black Holes & spin-offs

The popular notion of a black hole “sucking in everything” from its surroundings only happens very close to a black hole. Far away, the pull of the black hole is identical to that of anything else of the same mass. However, black holes do give rise to many remarkable phenomena such as extragalactic quasars and, in our own Galaxy, microquasars. This is because gravity is not the only law of physics that must be obeyed. Matter can be spun off from near black holes in the form of winds and jets that spread through their surroundings and thus cause black holes to have tremendous cosmic influence many light years beyond their event horizons. I will describe various approaches that I employ to investigate these phenomena, and their spin-offs.

This talk will be free for all, including non-members.

• Speaker: Prof Katherine Blundell
• Tuesday 11 March 2025, 18:00-19:30
• Venue: Pfizer Lecture Theatre, Department of Chemistry, Lensfield Road.
• Series: SciSoc – Cambridge University Scientific Society; organiser: Zhang Xianghao Jeffrey.

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Local structure of finite groups and fusion systems

Local finite group theory has been an important topic, particularly via the Classification of Finite Simple Groups. Fusion systems have helped simplify and extend much of the theory in the last 20 years and are starting to link group theory, representation theory, and algebraic topology. I will give an overview of some key ideas, introduce some examples, and discuss some of my results in the areas.

• Speaker: Baoyu Zhang, University of Birmingham
• Wednesday 12 March 2025, 16:30-17:30
• Venue: MR12.
• Series: Algebra and Representation Theory Seminar; organiser: Adam Jones.

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Helsing: Simulating a System of Systems

At Helsing, speed and correctness are key in delivering high quality products. The two are often in antithesis; it is difficult to quickly iterate over designs while keeping your codebase correct and vice versa. To build confidence in the systems we build, we use deterministic simulation concepts to enable full end-to-end testing and verification of our software through our in-house simulation platform called Prophecy. Prophecy aims to make simulating easy by providing libraries and services necessary to orchestrate simulations and build a system of systems. This allows other teams to test scenarios up-front and ensure their code and models are resilient to failure, and to run complex, distributed workflows through closed or open loop simulations. In this talk, we’ll be having a look at what deterministic simulation is in a nutshell, how Prophecy works, and how to simulate concurrent code in Rust using tokio.

Please register at the following link: https://forms.office.com/e/E2nCWEpkA9

Please note that it is not a requirement to sign up in order to attend the event

Some catering will be provided

• Speaker: Matei David
• Monday 17 March 2025, 13:05-13:55
• Venue: FW26, William Gates Building.
• Series: Technical Talks - Department of Computer Science and Technology ; organiser: Ben Karniely.

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Typological Diversity in NLP: What, Why and a Way Forward

To justify the generalisability of multilingual NLP research, multilingual language technology is frequently evaluated on ‘typologically diverse’ language selections. Yet, what this means often remains vague. In this talk, I first discuss what typological diversity means in NLP , and why it matters. Then, I introduce a framework for systematic language sampling, which is inspired by typological insights. Ultimately, the aim of this talk is to inspire research on linguistic typology in NLP that goes beyond merely leveraging databases, but rather incorporates research methodologies from linguistic typology.

• Speaker: Esther Ploeger (Aalborg University)
• Friday 07 March 2025, 12:00-13:00
• Venue: Zoom link: https://cam-ac-uk.zoom.us/j/4751389294?pwd=Z2ZOSDk0eG1wZldVWG1GVVhrTzFIZz09.
• Series: NLIP Seminar Series; organiser: Suchir Salhan.

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