Yuanjian Zhang

Electrochemiluminescence (ECL), the emission of light excited by electrochemical reactions, has drawn attention as a powerful tool for bioassays and environmental monitoring. Nonetheless, a limited understanding of the bulk electron transport (ET) process in solid‐state ECL emitters, particularly the mismatch between the electron diffusion length ( L _n ) at the photoelectrode and the light‐emitting layer thickness ( d ), significantly undermines the ECL efficiency ( Φ _ECL ) and impedes practical applications. Herein, we report L _n /d as a quantitative impedance‐derived kinetic‐matching descriptor of bulk electron transport in solid‐state ECL systems, and an empirical L _n / d range (0.9–1.2) for achieving high ECL efficiency is identified from the slope behavior of temporal ECL evolution curves. This strategy was further confirmed experimentally across different ECL systems, including metal‐organic frameworks (MOF), poly(heptazine imide) (PHI), and carbon nitride with tunable band structures. The optimal L _n / d ratio range enabled superior electron transport and mass transfer, yielding a record‐high cathodic ECL efficiency for carbon nitride (CN) and enabling a visual tetracycline (TC) sensor with an excellent detection range and limit.

Electrochemiluminescence (ECL), the emission of light excited by electrochemical reactions, has drawn attention as a powerful tool for bioassays and environmental monitoring. Nonetheless, a limited understanding of the bulk electron transport (ET) process in solid‐state ECL emitters, particularly the mismatch between the electron diffusion length ( L _n ) at the photoelectrode and the light‐emitting layer thickness ( d ), significantly undermines the ECL efficiency ( Φ _ECL ) and impedes practical applications. Herein, we report L _n /d as a quantitative impedance‐derived kinetic‐matching descriptor of bulk electron transport in solid‐state ECL systems, and an empirical L _n / d range (0.9–1.2) for achieving high ECL efficiency is identified from the slope behavior of temporal ECL evolution curves. This strategy was further confirmed experimentally across different ECL systems, including metal‐organic frameworks (MOF), poly(heptazine imide) (PHI), and carbon nitride with tunable band structures. The optimal L _n / d ratio range enabled superior electron transport and mass transfer, yielding a record‐high cathodic ECL efficiency for carbon nitride (CN) and enabling a visual tetracycline (TC) sensor with an excellent detection range and limit.

Emerging mechanistic strategies and advanced mechanism evaluation techniques for fueling advances in bioanalysis and imaging.

Understanding and regulating photocurrent generation in semiconductors, particularly the control of polarity, is central to photoelectrochemical (PEC) system design. While engineered heterojunctions enable wavelength-dependent polarity switching, they require complex architectures. Light intensity, by contrast, is far more readily tuned but has long been limited to modulating photocurrent magnitude. Herein, we report that surface states, which participate in photoinduced carrier transfer, can mediate light-intensity-dependent photocurrent polarity reversal in single-component semiconductors of both n- and p-type (e.g., carbon nitride, CdTe quantum dots, and BiOI). Mechanism studies reveal that in the photocurrent switching potential (E _ps ) region, where the built-in potential is attenuated, surface state occupation, dictated by illumination intensity, governs the direction of charge transfer. This surface-state-mediated mechanism establishes light intensity as an orthogonal dimension for adaptive photoresponsivity, bypassing the need for heterojunction engineering. As a proof of concept, a dopamine PEC biosensor built on this principle achieves exceptional selectivity without conventional biorecognition units, where photocurrent polarity itself serves as the recognition dimension.

Because of the unique water/organic (w/o) interface structure, the interface between two immiscible electrolyte solutions (ITIES) is regarded as an effective biomimetic model for cell membranes and has been extensively used in drug delivery research. Nonpolar organic solvents such as dichloroethane (DCE) have been widely adopted as the organic phase in ITIES, yet the nonpolar molecular structure of the solvent greatly differs from the components of cell membranes, which may influence the ion transfer process across the w/o interface. Thus, in this work, tributyrin (Tri), an organic solvent structurally analogous to glycerophospholipids, was employed as a moderately polar oil phase in ITIES. Although the water/tributyrin (w/Tri) interface exhibited a narrower potential window and significantly slower ion transfer kinetics for tetrabutylammonium (TBA) compared to the conventional water/DCE (w/DCE) interface, a considerably faster transfer kinetics was observed at w/Tri than at w/DCE for a polar ion tolazoline (TOZ). This suggested that ion transfer kinetics depended on the polarity of both the ion and the organic solvent and was further confirmed by systematic measurements of ions with varying molecular polarities. On the basis of this, the direct ionophore-free transfers of the metal ions Cs+ and K+ were successfully achieved at the w/Tri interface for the first time. This finding not only expands the understanding of ITIES systems but also opens up new approaches to developing biomimetic sensing interfaces for polar bioactive molecules.

Life is sustained by diverse far‐from‐equilibrium enzymatic reaction networks that reversibly sense and respond to environmental signals and precisely regulate biological functions. A key goal of chemistry is to develop enzymatic reaction networks (ERNs) with life‐like properties. Here we introduce an overview of the emerging fields of synthetic ERNs, which aims at mimicking hallmarks of living systems by combining enzymatic reactions with far‐from‐equilibrium processes. We first elucidate the concepts, mechanisms, and nonlinear features of far‐from‐equilibrium enzymatic reaction networks, and then we survey synthetic enzymatic reaction networks with various complex temporal dynamics. We further emphasize the functional applications of synthetic enzymatic reaction networks in diverse fields, such as autonomous nanomotors, programmable transient materials, molecular computing systems, and life‐like artificial cells, and also delve into their future research directions and associated challenges. Engineered far‐from‐equilibrium ERN is a major first step in harnessing the design principles of life for construction of the active molecular devices that exist in nature.

Achieving pathway-selective catalysis in single-atom nanozymes (SAzymes) is highly significant yet challenging, especially for heme-like M–N4 structured SAzymes, which demonstrate powerful enzyme-like catalytic efficiency and broad applicability. Inspired by the axial-ligand-regulated local electric fields oriented along the Fe═O axis in natural heme metalloenzymes, which switch selectivity within a shared metal–oxo manifold, we developed FeNSC–O SAzymes featuring axial O coordination stabilized by sulfur doping, achieving a catalase/peroxidase-like (CAT/POD) selectivity up to 7.4 times greater than that of planar oxygen-doped FeNC–O SAzymes. Low-temperature EPR and magnetic susceptibility measurements revealed that axial O coordination shifts the Fe center from the high-spin configuration in FeNC–O to the intermediate-spin state in FeNSC–O. Further DFT analyses demonstrated that the axial O ligand induces strong σ hybridization between Fe 3dz2–O 2pz orbitals and π hybridization between the Fe 3dxz/3dyz–O 2px/2py orbitals. This orbital reconstruction reduces the Fe spin polarization and is accompanied by electron withdrawal from the Fe center, thereby weakening the Fe 3d–O 2p orbital overlap and charge transfer to oxygen-containing intermediates. Consequently, H2O2 adsorption and its dissociative conversion to (*O + H2O) are limited, suppressing the POD-like pathway. Meanwhile, weakened O2 binding facilitates O2 release, thereby enhancing the CAT-like pathway. Together, these effects switch H2O2 activation toward CAT-like disproportionation and enhance CAT/POD selectivity. Furthermore, encapsulating FeNSC–O within asymmetric hollow nanoreactors enabled the construction of H2O2-responsive self-propelled nanomotors capable of active inflammatory-cell penetration and intracellular ROS scavenging, demonstrating their promising potential for targeted therapy and precision medicine.

Multiple technologies have been developed to reconcile the trade-off between sensitivity and portability, which is a persistent fundamental challenge in chemical sensing. Among them, electrochemiluminescence (ECL) has the advantages of simple device configuration and outstanding sensitivity based on the transduction of electrochemical signals into optical readouts. However, this is based on multi-step interfacial electron transfer, wherein the concomitant efficiency losses and areadependent signal intensity inherently constitute the primary limitations. Herein, a novel photochargeable wireless ECL (PC-Wireless-ECL) system is established based on a bifunctional carbon nitride (CN). This strategy boosts the ECL signal intensity by eliminating the dependence on the electrode dimensions and decoupling the excitation and emission processes temporally. By constructing portable bifunctional CN vials coupled with a miniaturized light intensity sensor, this system revolutionizes the conventional ECL measurement paradigm and realizes on-site, rapid, and highly sensitive screening of water toxicity, thereby offering a new strategy for next-generation in-field analytical technologies.

We synthesize three aryl-substituted [6]helicene derivatives and investigate their reactivity in the Scholl reaction. The phenylnaphthyl substrate exhibits unique regioselectivity and rearrangement involving competing 1,2-aryl migrations, as elucidated by density functional theory calculations. The obtained π-extended helicenes are characterized by X-ray diffraction. 1 featuring a perylenyl moiety displays bathochromically shifted absorption and emission compared to triple helicenes 2–4. Circular dichroism and circularly polarized luminescence spectra demonstrate that optically pure 1 and 3 show absorption and luminescence dissymmetry factors of 10–3.