Nanoscience News (<front>)

A core–shell ternary electrode (Opt-SWCNTs/PEDOT:PSS/IL) is developed via a simple two-step dispersion and vacuum filtration process, with component ratios optimized to achieve excellent mechanical toughness and electrical conductivity based on simulation results. The resulting actuators demonstrate high strain and blocking force, enabling precise gripping and complex deformation, showing great potential for soft robotics and next-generation electrochemical actuators.

Abstract

Ionic actuators based on composite electrodes consisting of nanomaterials and conducting polymer typically offer the advantages of low-voltage operation and high stability, however, electrode preparation using conventional mixing suffers from issues of ineffective dispersion of nanomaterials, greatly diminishing their synergistic effects. Here, the ternary electrode system based on SWCNTs/PEDOT: PSS/ionic liquid using the two-step dispersion process is optimized, achieving a uniformly coated core–shell structure with high conductivity (≈392.4 S cm−1). The ions migration process is analyzed according to the core–shell model, further optimization of the ternary electrode and device structure enables the actuator to realize the peak-to-peak strain per volt reaching 1.3% V−1 and normalized blocking force of 0.15 MPa V−1 (≈89.2 times its own weight), with stable performance maintained over 1 million cycles. Therefore, the actuator can be utilized for the assembly of multi-clawed grippers to grasp precision components or larger objects. Multiple connected actuators fulfill a complex deformation, indicating promising applications in smart grippers, bioinspired robotics, and human–machine interaction.

Carbon-based hole-transport-layer-free perovskite solar cells present a cost-effective and stable photovoltaic alternative but suffer from low efficiency due to the absence of back surface field (BSF). In this work, trityl tetrakis(pentafluorophenyl)borate is utilized to engineer dual BSFs, significantly enhancing open-circuit voltage and leading to a champion efficiency of 20.79%—marking a substantial improvement in device performance.

Abstract

Carbon-based hole transport layer-free (C-HTL-free) perovskite solar cells (PSCs) are promising for low-cost and stable photovoltaics, but the HTL absence deteriorates their power conversion efficiency (PCE) due to the lack of back surface field (BSF). In this work, the benefits of forming dual BSFs in improving the PCE of C-HTL-free PSCs are first investigated by simulation. Then, trityl tetrakis(pentafluorophenyl)borate (Tr+TPFB−) is introduced into the C-HTL-free PSCs by post-treatment for the first time, which enables the formation of dual BSFs. TPFB− passivates n-doping defects in perovskite and leads to the formation of perovskite n-p homojunction, while Tr+ extracts electrons from carbon and lowers its work function, which succeeds realizing dual BSFs. This improves the separation and extraction of photocarriers within the device, which is evidenced by the photoluminescence lifetime imaging of the device cross-section for the first time. As a result, the average open-circuit voltage increases significantly by about 70 mV, which largely contributes to the improvement of PCE with a champion value of 20.79% obtained.

Benzenesulfonate monomers undergo in situ self-polymerization during the crystallization process of perovskite, providing more uniform passivation for perovskite defects than single molecules. The in situ formed polymer also facilitates the growth of large grain domains and the charge transport, offering an efficiency of 25.34% for small-area perovskite solar cells and 21.54% for mini-modules with an active area of 14.0 cm2.

Abstract

Realizing high-quality perovskite films through uniform defect passivation and crystallization control is pivotal to unlocking the potential of scalable applications. However, prevalent small-molecule additives are inherently susceptible to the crystallization dynamics of perovskites, resulting in non-uniform distribution within the crystalline film and impeding consistent passivation and precise crystallization control. While polymers offer improved uniformity, their poor solubility restricts practical applications. To overcome this limitation, an in situ self-polymerization strategy is employed, enabling homogeneous coordination between sulfonate-containing additives and undercoordinated lead cations. This approach enhances perovskite film quality, promotes larger crystalline grain domains, and facilitates more efficient charge transport across grain domain boundaries. As a result, perovskite solar cells (PSCs) achieve a remarkable power conversion efficiency of 25.34% in small-area devices and 21.54% in 14.0 cm2 mini-modules, accompanied by exceptional operational stability. These findings highlight in situ polymerization as an effective strategy for leveraging sulfonate additives to overcome distribution challenges, advancing the scalable fabrication of efficient and stable PSCs.

A universal weakly-solvated electrolyte design principle is established for phosphorus-based anodes through systematic evaluation. Based on this criterion, the fluorinated solvent of FEC emerges as the optimal co-solvent, effectively suppressing the dissolution of lithium polyphosphides while enhancing desolvation/charge-transfer kinetics and simultaneously fostering a stable inorganic-rich SEI layer. This rational strategy addresses critical interfacial challenges in high-performance phosphorus-based battery systems.

Abstract

hosphorus-based anodes hold promise for energy storage due to their high theoretical capacity and favorable lithiation potential. However, their practical application is hindered by sluggish reaction kinetics and irreversible capacity loss, primarily attributed to multiphase lithiation/delithiation reactions and the dissolution of lithium polyphosphide intermediates. Herein, a universal design principle of weakly solvated electrolytes (WSEs) tailored for phosphorus-based anodes is proposed. Combined with a high dielectric constant, and significant dipole moment, a fluorinated cosolvent is incorporated into a WSE to effectively suppress the dissolutions of lithium polyphosphides, enhance interfacial stability, and accelerate reaction kinetics. With this electrolyte, a phosphorus-based anode achieves a remarkable capacity of 2615.2 mAh g⁻¹ at 1C, maintaining 91.7% capacity retention over 1000 cycles. Even at a high rate of 4 C, it delivers 2210.7 mAh g⁻¹ with an exceptional retention of 96.7% after 1500 cycles. Furthermore, at 0 °C, the anode sustains a capacity of 2016.7 mAh g⁻¹, with 97% retention after 300 cycles at 1C. This study provides a novel electrolyte design strategy to regulate the solvation sheath, paving the way for high-rate, long-cycle phosphorus-based anodes suitable for fast-charging applications.

Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE01295C, PaperHouwei He, Zhongliao Wang, Jinfeng Zhang, Shavkat Mamatkulov, Olim Ruzimuradov, Kai Dai, Jingxiang Low, Yue Li
Photocatalytic hydrogen peroxide (H2O2) production (PHP) represents a promising strategy for substituting the anthraquinone process, yet the sluggish redox kinetics causes strong oxidizing superoxide intermediate rapid accumulation, resulting in poor...
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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00652J, PaperXiao Fang, Bonan Li, Jiao Huang, Chunlian Hu, Xu Yang, Pengfei Feng, Xiaoyu Dong, Junhao Wu, Yuanyuan Li, Yong Ding
Artificial photosynthesis is a potential hydrogen peroxide (H2O2) production strategy, but the poor charge separation and transfer limit the photocatalytic efficiency. Here, the sodium/potassium poly(heptazine imide) (NaK-PHI) photocatalyst with the...
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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D4EE04857A, PaperMingzhe Yang, Tongle Chen, gongrui Wang, Xiaofeng Li, Yangyang Liu, Xuanxuan Ren, Ying Zhang, Lu Wu, Li Song, Juncai Sun, Zhong-Shuai Wu
Lithium-rich manganese-based oxides (LRMOs) are promising high-specific-energy cathode materials for lithium-ion batteries (LIBs) but face issues of voltage decay and poor cyclability rooted in ireversible O/Mn redox. Herein we present...
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This work proposes a self-assembled monolayer (SAM) with reconstructed hydrogen-bond network to form an efficient three-phase interface that facilitates CO2 mass transport and maintained an ideal H+/e− transfer pathway. The optimized catalyst maintains a high current density of 502.5 mA cm−2 with over 85% C2+ Faradaic efficiency and operated very stably.

Abstract

CO2 electrolysis is a promising approach to reduce CO2 emissions while achieving high-value multi-carbon (C2+) products. Except for the key role of electrocatalyst for electrochemical CO2 reduction reaction (CO2RR), Reaction microenvironment is another critical factor influencing catalytic performance for these catalysts. Herein, a self-assembled monolayer (SAM) is proposed with reconstructed hydrogen-bond network to form an efficient three-phase interface that admins mass transport and ion-electron transfer. This approach is realized by co-assembly of the fluorinated SAM (F-SAM) and siloxane on commercial Cu catalyst (Cu@F-Si composite catalyst). Molecular dynamics simulations (MDS) and interfacial species analysis show that the F-SAM effectively facilitates CO2 mass transport, while the siloxane hydrogen bond network maintains an ideal H+/e− transfer pathway. Combined with density functional theory (DFT) calculations, this strategy reveals the mechanism by which optimizing *H/*CO coverage enhances C2+ product selectivity. Ultimately, the Cu@F-Si catalyst maintains a high current density of 502.5 mA cm−2 with over 85% C2+ Faradaic efficiency (FE) and operates stably for more than 100 h at ≈300 mA cm−2. This interface engineering strategy offers a promising solution for improving the efficiency of CO2RR, with broader applications in multiphase catalytic systems.

This perspective critically examines HE approaches in SEs, highlighting how compositional complexity induces system disorder and local-structure evolution to enhance stability and properties. While HE concepts are attractive, establishing rigorous structure-property relationships requires further investigation. The discussion aims to guide future research in this promising field by clarifying key challenges and opportunities in HE-based electrolyte design.

Abstract

As the key material for the all-solid-state batteries (ASSBs), solid electrolytes (SEs) have attracted increasing attention. Recently, a novel design strategy−high-entropy (HE) approach is frequently reported to improve the ionic conductivity and electrochemical performance of SEs. However, the fundamental understandings on the HE working mechanism and applicability evaluation of HE concept are deficient, which would impede the sustainable development of a desirable strategy to enable high-performance SEs. In this contribution, the essence of HE-related approaches and their positive effects on SEs are evaluated. The reported HE strategy stems from complex compositional regulations. The derived structural stability and enhanced property are originally from the modulated system disorder and subtle local-structure evolutions, respectively. While HE ardently describes the increased entropy/disorder during the modification of prevailing SEs, rigorous experimental formulations, and direct correlations between the HE structures and desired properties are necessary to be established. This perspective would be a timely and critical overview for the HE approaches in the context of SEs, aiming to stimulate further discussion and exploration in this emerging research direction.

Halide solid electrolytes, an emerging family of materials, encounter anodic stability challenges that limit their application. By synthesizing Li3YbCl6 and Li3LuCl6 and incorporating a Li6PI3 interlayer, this study achieves lithium-stable halide electrolytes with reduced interface resistance and enhanced critical current density. These advancements pave the way for safer, high-energy-density batteries for electric transportation.

Abstract

All-solid-state lithium-metal batteries (ASSLMBs) are promising for transportation electrification due to their superior safety and high energy density. Lithium halide electrolytes provide excellent processing flexibility, high ionic conductivity, and anodic stability (>4.1 V), making them highly compatible with high-voltage cathodes, surpassing sulfide electrolytes (<2.1 V). Nevertheless, halide electrolytes suffer from low cathodic stability and form an electronically conductive interphase with lithium, resulting in a critical current density (CCD) of nearly zero. Herein, Li3YbCl6 electrolytes are synthesized that are kinetically stable with lithium by forming an electronic insulating solid electrolyte interphase. Guided by critical overpotential criteria, a PI3 interlayer is designed that transforms into Li6PI3 upon contact with lithium, substantially reducing the interfacial resistance of Li3YbCl6 against lithium to 34 Ω and achieving a high critical overpotential of 114 mV. By substituting Yb with Lu, Li3LuCl6 electrolytes with Li6PI3 interlayers reach a CCD of 1.0 mA cm−2 at a capacity of 1.0 mAh cm−2, comparable to sulfide electrolytes but with higher oxidation stability. Additionally, Li6PI3 enables stable cycling of Li//Li cells with Li3LuCl6 electrolytes at 0.5 mA cm−2 for 400 cycles and maintains 86.5% capacity in Li//LiCoO2 cells after 220 cycles at 30 °C, paving the way for high-performance ASSLMBs.

Photonic Pseudomagnetism and Landau Levels

When electrons moving in a two-dimensional plane are subject to a perpendicular magnetic field they move in circles called cyclotron orbits as a result of the Lorentz force. Treated quantum mechanically, these orbits become quantized like the orbitals of an atom, forming highly degenerate states called Landau levels. In this talk, I will show how we made photons “feel” a magnetic field and thus form Landau levels in a photonic crystal, despite the fact that photons carry no charge and thus cannot experience the Lorentz force. This increases the strength of interaction between light and matter, which has implications in quantum optics and integrated photonics. Time permitting, I will discuss the related topic of how edge states in a “Chern insulator” photonic crystal can be used to slow down light in a photonic chip over a wide bandwidth.

• Speaker: Mikael Rechtsman, Penn State
• Friday 09 May 2025, 14:00-15:00
• Venue: Seminar Room 3, RDC.
• Series: Theory of Condensed Matter; organiser: Gaurav.

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CamVet Clinial Research Grants

Abstract not available

• Speaker: Bruno Lopes, Jose Novo Matos, and Tom Kearns, Department of Veterinary Medicine
• Friday 26 September 2025, 08:45-10:00
• Venue: LT2.
• Series: Friday Morning Seminars, Dept of Veterinary Medicine; organiser: Fiona Roby.

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Title to be confirmed

Abstract not available

• Speaker: Annalaura Rebucci, MPI Leipzig
• Monday 26 May 2025, 14:00-15:00
• Venue: MR13.
• Series: Partial Differential Equations seminar; organiser: Amelie Justine Loher.

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Superdiffusivity for a diffusion in a critically-correlated incompressible random drift

We consider an advection-diffusion (or “passive scalar”) equation with a divergence-free vector field, which is a stationary random field exhibiting “critical” correlations. Predictions from physicists in the 80s state that, almost surely, this equation should behave like a heat equation at large scales, but with a diffusivity that diverges as the square root of the log of the scale. In joint work with Ahmed Bou-Rabee and Tuomo Kuusi, we give a rigorous proof of this prediction using an iterative quantitative homogenization procedure, which is a way of formalizing a renormalization group argument. The idea is to consider a scale decomposition of the vector field, and coarse-grain the equation, scale-by-scale. The random swirls of the vector field at each scale enhance the effective diffusivity. As we zoom out, we obtain an ODE for the effective diffusivity as a function of the scale, allow us to deduce that it diverges at the predicted rate. Meanwhile, new coarse-graining arguments allow us to rigorously integrate out the smaller scales in the equation and prove the result.

• Speaker: Scott Armstrong, Sorbonne Université
• Monday 12 May 2025, 14:00-15:00
• Venue: MR13.
• Series: Partial Differential Equations seminar; organiser: Amelie Justine Loher.

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Vertical mixing and associated biogeochemical fluxes via radium isotopes

The coastal ocean is a highly dynamic and vital biogeochemical mediator between land and sea. Coastal waters frequently experience poor water quality derived from land-based anthropogenic pressure, which is often attributed to surface water sources, such as rivers. Subsurface sources (e.g., submarine groundwater discharge, benthic fluxes), however, often rival or exceed river contributions to coastal water and chemical budgets. Yet subsurface sources are understudied because they are challenging to quantify.

In this talk, I will first give a broad overview on quantifying subsurface flows using U-Th series geochemical tracers (radium, radon). Then I will present an ecosystem-scale study across the Baltic Sea, where we used 224Ra to quantify vertical mixing across a largely hypoxic deep water column. We collected radium and solute (e.g., dissolved silicate) bottom water profiles from 50 stations along a ~5000 km cruise track in the Baltic Sea. 224Ra-derived vertical mixing rates were on the order of 10-4 m2/s, well-within range of previous local-scale estimates based on modeling and sediment core incubations. Diffusive solute fluxes were also similar in magnitude to previous studies. Overall, this talk will highlight an innovative method for quantifying diffusive fluxes and contextualize findings in terms of broader biogeochemical significance.

• Speaker: Tristan McKenzie, Uni of Gothenberg
• Thursday 15 May 2025, 11:30-12:30
• Venue: Open Plan Area, Institute for Energy and Environmental Flows, Madingley Rise CB3 0EZ.
• Series: Institute for Energy and Environmental Flows (IEEF); organiser: Catherine Pearson.

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Measuring Political Bias in Large Language Models

Large language models (LLMs) are helping millions of users to learn and write about a diversity of issues. In doing so, LLMs may expose users to new ideas and perspectives, or reinforce existing knowledge and user opinions. This creates concerns about political bias in LLMs, and how these biases might influence LLM users and society. In my talk, I will first discuss why measuring political biases in LLMs is difficult, and why most evidence so far should be approached with skepticism. Using the Political Compass Test as a case study, I will demonstrate critical issues of robustness and ecological validity when applying such tests to LLMs. Second, I will present our approach to building a more meaningful evaluation dataset called IssueBench, to measure biases in how LLMs write about political issues. I will describe the steps we took to make IssueBench realistic and robust. Then, I will outline our results from testing state-of-the-art LLMs with IssueBench, including clear evidence for issue bias, striking similarities in biases across models, and strong alignment with Democrat over Republican voter positions on a subset of issues. Bio: Paul is a postdoctoral researcher in the MilaNLP Lab at Bocconi University, working on evaluating and improving the alignment and safety of large language models, as well as measuring their societal impacts. For his recent work in this area, he won Outstanding Paper at ACL and Best Paper at NeurIPS D&B. Before coming to Milan, Paul completed his PhD at the University of Oxford, where he worked on LLMs for hate speech detection. During his PhD, Paul also co-founded Rewire, a start-up building AI for content moderation, which was acquired by another large online safety company in 2023.

• Speaker: Paul Röttger (Bocconi University)
• Friday 16 May 2025, 12:00-13:00
• Venue: Room FW26 with Hybrid Format. Here is the Zoom link for those that wish to join online: https://cam-ac-uk.zoom.us/j/4751389294?pwd=Z2ZOSDk0eG1wZldVWG1GVVhrTzFIZz09.
• Series: NLIP Seminar Series; organiser: Suchir Salhan.

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Title to be confirmed

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• Speaker: Jujian Zhang (Imperial College London) and Arnaud Mayeux (The Hebrew University of Jerusalem)
• Thursday 19 June 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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Completeness Theorems for Variations of Higher-Order Logic

Mike Gordon’s Higher-Order Logic (HOL) is one of the most important logical foundations for interactive theorem proving. The standard semantics of HOL , due to Andrew Pitts, employs a downward closed universe of sets, and interprets HOL ’s Hilbert choice operator via a global choice function on the universe.

In this talk, I introduce a natural Henkin-style notion of general model corresponding to the standard models. By following the Henkin route of proving completeness, I discover an enrichment of HOL deduction that is sound and complete w.r.t. these general models. Variations of my proof also yield completeness results for weaker deduction systems located between standard and (fully) enriched HOL deduction, relative to less constrained models.

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Meeting ID: 898 5609 1954 Passcode: ITPtalk

• Speaker: Andrei Popescu (University of Sheffield)
• Thursday 15 May 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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Algebraic Geometry in Mathlib

Algebraic geometry is the study of systems of polynomial equations, and more broadly, the interplay between commutative algebra and geometry. It is a field with a rich history and a modern foundation, drawing heavily on ring theory, topology, and category theory. Over the years, mathlib, the Lean 4 library of formalized mathematics, has developed a sizable body of algebraic geometry. In this talk, I will present an overview of the current state of the library, highlighting key developments, challenges encountered along the way, and the solutions we have adopted.

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• Speaker: Andrew Yang (Imperial College, London)
• Thursday 08 May 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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The myth of the naïve empiricist

Abstract not available

CANCELLED

• Speaker: Michael Bycroft (University of Warwick)
• Wednesday 07 May 2025, 13:00-14:30
• Venue: Seminar Room 2, Department of History and Philosophy of Science.
• Series: CamPoS (Cambridge Philosophy of Science) seminar; organiser: Miguel Ohnesorge.

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