arXiv subjects

Boxuan Zhou

Publications and source records attributed to Boxuan Zhou.

6 recordsLinked to original sources

arXiv2026

Proton-electron coupled catalyst for ionomer-free electrochemical energy conversion

Efficient electrochemical energy devices are vital to renewable energy technology, yet coordinating the effective flow of electrons, ions, and chemical species continues to be a major challenge. In conventional proton-exchange membrane fuel cell (PEMFC) catalyst layers, proton and electron transport are supplied separately through percolating carbon networks and ionomer binders, rendering the catalyst largely passive and imposing fundamental trade-offs between reactant accessibility, ionic conductivity, and catalyst activity. Here, we introduce a one-dimensional proton-electron coupled catalyst (PECC) design, a transport-integrated electrocatalyst architecture in which the catalyst itself simultaneously supplies electronic and protonic transport to catalyst active sites. Using this PECC, PEMFCs can have an ionomer-free cathode catalyst layer (CCL), resulting in a dramatic 95% reduction in non-Fickian oxygen transport and boosting power density by 34% and 85% compared to traditional CCLs, with cathode Pt loadings of approximately 0.090 mg/cm^2 and 0.037 mg/cm^2, respectively. Meanwhile, PECC retains 65% of its mass activity and exhibits 32% higher power density than its ionomer-based CCL counterpart after 30k accelerated stressed test. Similar mass transport improvements have been observed in the electrochemical hydrogen pump (EHP) using PECC in the catalyst layers. Molecular dynamics simulations show the PECC's proton conductivity is 249% higher than Nafion. This PECC catalyst structure addresses core transport problems in PEMFCs, leading to almost 20% improvement in fuel efficiency and opens up new possibilities for designing high-performance, cost-effective electrochemical devices.

cond-mat.mtrl-sci↗

arXiv2026

Subwavelength Coherent Scaling of High-Order Nonlinear Light Generation in Bulk Monolayer MoS2 Thin Films

Monolayer transition metal dichalcogenides (e.g., MoS2) exhibit exceptionally large optical nonlinearities for high-order nonlinear light generation (NLG), yet their inherent atomic thickness fundamentally limits light-matter interactions and thus conversion efficiency. Here, we overcome this intrinsic trade-off using a solution-processed bulk monolayer MoS2 (BM-MoS2) architecture composed of electronically decoupled MoS2 monolayers separated by organic interlayers. This layered superstructure preserves the exceptional intrinsic nonlinear susceptibility of monolayer MoS2 while enabling scalable interaction length. In the subwavelength regime, the NLG scales nearly quadratically with layer number (N1.8), confirming the constructive buildup of nonlinear fields across stacked monolayers. As a result, a 100-nm-thick BM-MoS2 thin film exhibits colossal high-order NLG, including four-wave mixing and high-harmonic generation. The generated nonlinear beam is directly visible to the naked eye and exhibits broad spectral tunability spanning approximately 1000 nm in the mid-IR, enabling mid-IR-to-visible upconversion spectroscopy for resolving molecular vibrational fingerprints. By uniting monolayer-scale nonlinear susceptibility with bulk interaction length and coherent field buildup, BM-MoS2 establishes a thin-film platform for ultra-compact and substrate-agnostic nonlinear photonic systems beyond the constraints of conventional single crystals.

physics.optics↗

arXiv2024

Electrically functionalized body surface for deep-tissue bioelectrical recording

Directly probing deep tissue activities from body surfaces offers a noninvasive approach to monitoring essential physiological processes1-3. However, this method is technically challenged by rapid signal attenuation toward the body surface and confounding motion artifacts4-6 primarily due to excessive contact impedance and mechanical mismatch with conventional electrodes. Herein, by formulating and directly spray coating biocompatible two-dimensional nanosheet ink onto the human body under ambient conditions, we create microscopically conformal and adaptive van der Waals thin films (VDWTFs) that seamlessly merge with non-Euclidean, hairy, and dynamically evolving body surfaces. Unlike traditional deposition methods, which often struggle with conformality and adaptability while retaining high electronic performance, this gentle process enables the formation of high-performance VDWTFs directly on the body surface under bio-friendly conditions, making it ideal for biological applications. This results in low-impedance electrically functionalized body surfaces (EFBS), enabling highly robust monitoring of biopotential and bioimpedance modulations associated with deep-tissue activities, such as blood circulation, muscle movements, and brain activities. Compared to commercial solutions, our VDWTF-EFBS exhibits nearly two-orders of magnitude lower contact impedance and substantially reduces the extrinsic motion artifacts, enabling reliable extraction of bioelectrical signals from irregular surfaces, such as unshaved human scalps. This advancement defines a technology for continuous, noninvasive monitoring of deep-tissue activities during routine body movements.

physics.med-ph↗

arXiv2023

Broadband nonlinear modulation of incoherent light using a transparent optoelectronic neuron array

Nonlinear optical processing of ambient natural light is highly desired in computational imaging and sensing applications. A strong optical nonlinear response that can work under weak broadband incoherent light is essential for this purpose. Here we introduce an optoelectronic nonlinear filter array that can address this emerging need. By merging 2D transparent phototransistors (TPTs) with liquid crystal (LC) modulators, we create an optoelectronic neuron array that allows self-amplitude modulation of spatially incoherent light, achieving a large nonlinear contrast over a broad spectrum at orders-of-magnitude lower intensity than what is achievable in most optical nonlinear materials. For a proof-of-concept demonstration, we fabricated a 10,000-pixel array of optoelectronic neurons, each serving as a nonlinear filter, and experimentally demonstrated an intelligent imaging system that uses the nonlinear response to instantly reduce input glares while retaining the weaker-intensity objects within the field of view of a cellphone camera. This intelligent glare-reduction capability is important for various imaging applications, including autonomous driving, machine vision, and security cameras. Beyond imaging and sensing, this optoelectronic neuron array, with its rapid nonlinear modulation for processing incoherent broadband light, might also find applications in optical computing, where nonlinear activation functions that can work under ambient light conditions are highly sought.

physics.optics↗

arXiv2023

Signatures of Chiral Superconductivity in Chiral Molecule Intercalated Tantalum Disulfide

Chiral superconductors, a unique class of unconventional superconductors in which the complex superconducting order parameter winds clockwise or counter-clockwise in the momentum space, represent a topologically non-trivial system with direct implications for topological quantum computing. Intrinsic chiral superconductors are extremely rare, with only a few arguable examples including heavy fermion metals (UTe$_2$, UPt$_3$) and perovskite superconductor Sr$_2$RuO$_4$. Chiral molecules with neither mirror nor inversion symmetry have been widely investigated, in which the spin degeneracy may be lifted by the molecular chirality. Thus, a combination of superconductivity with chiral molecules may lead to a spin-polarized ground state for realizing chiral superconductivity. Herein we report the first investigation of unconventional superconductivity in chiral molecule intercalated tantalum disulfide (TaS$_2$) and reveal key signatures of chiral superconductivity. Little-Parks measurements demonstrate a robust and reproducible half-flux quantum phase shift in both left- and right-handed chiral molecule intercalated TaS$_2$, which is absent in pristine TaS$_2$ or achiral molecule intercalated TaS$_2$, highlighting the essential role of molecular chirality in inducing unconventional superconductivity. The robust half-flux quantum phase shift demonstrates unconventional superconductivity and constitutes strong evidence supporting a chiral superconducting ordering parameter. Critical current measurements at lower temperature reveal a peculiar asymmetric phase shift under opposite supercurrent, with a relative phase difference approaching the unity of {\pi} at below 0.5 K, further supporting topologically non-trivial superconductivity. Our study signifies the potential of hybrid superlattices with intriguing coupling between the crystalline atomic layers and the self-assembled molecular layers.

cond-mat.supr-con↗

arXiv2021

Self-powered Filterless On-chip Full-Stokes Polarimeter

The detection of polarization states of light is essential in photonic and optoelectronic devices. Currently, the polarimeters are usually constructed with the help of waveplates or a comprehensive metasurface, which will inevitably increase the fabrication complexity and unnecessary energy loss. Here, we have successfully demonstrated a self-powered filterless on-chip full-Stokes polarimeter based on a single-layer MoS2/few-layer MoS2 homojunction. Combining the built-in electric field enhanced circular photogalvanic effect with the intrinsic optical anisotropy of MoS2 between in-plane and out-of-plane direction, the device is able to conveniently sense four Stokes parameters of incident light at zero bias without requiring an extra filtering layer, and can function in the wavelength range of 650-690 nm with acceptable average errors. Besides, this homojunction device is easy to integrate with silicon-based chips and could have much smaller sizes than metasurface based polarimeters. Our study thus provides an excellent paradigm for high-performance on-chip filterless polarimeters.

physics.optics↗