Guangyuan Feng

Photonic synaptic electrocatalysts encode catalytic activity as a writable, retainable state under optical stimulation, enabling history‐dependent performance modulation with potential relevance to scenarios such as intermittent solar illumination and artificial metabolic learning systems. However, most photo‐assisted electrocatalysts are stateless, showing only transient activity enhancement under illumination that vanishes once the light is removed. Here, we establish a photonic synaptic electrocatalyst based on a bimetallic covalent organic framework (Co–Ni─COF), in which optical stimulation writes synaptic information into the catalytic state, and oxygen evolution serves as a stringent functional readout. During electrochemical reactions, Co─Ni─COF shows strong photonic synaptic behavior, featuring excitatory postsynaptic current responses, tunable synaptic plasticity, transitions from short‐term to long‐term plasticity, learning–forgetting–relearning behavior, and long‐term memory retention. Mechanistic investigations reveal that this light‐written and retained state originates from strengthened electronic coupling between Co and Ni centers, promoted charge delocalization and intermetallic charge transfer, and the accumulation of metastable Co(III) active species together with key oxygenated intermediates (*OOH, *OO). Notably, a substantial fraction of enhanced catalytic activity is preserved for hours in the dark, maintaining ∼127% higher than the initial state after 3 h, highlighting its potential for efficient energy conversion under intermittent solar illumination.

Photonic synaptic electrocatalysts encode catalytic activity as a writable, retainable state under optical stimulation, enabling history‐dependent performance modulation with potential relevance to scenarios such as intermittent solar illumination and artificial metabolic learning systems. However, most photo‐assisted electrocatalysts are stateless, showing only transient activity enhancement under illumination that vanishes once the light is removed. Here, we establish a photonic synaptic electrocatalyst based on a bimetallic covalent organic framework (Co–Ni─COF), in which optical stimulation writes synaptic information into the catalytic state, and oxygen evolution serves as a stringent functional readout. During electrochemical reactions, Co─Ni─COF shows strong photonic synaptic behavior, featuring excitatory postsynaptic current responses, tunable synaptic plasticity, transitions from short‐term to long‐term plasticity, learning–forgetting–relearning behavior, and long‐term memory retention. Mechanistic investigations reveal that this light‐written and retained state originates from strengthened electronic coupling between Co and Ni centers, promoted charge delocalization and intermetallic charge transfer, and the accumulation of metastable Co(III) active species together with key oxygenated intermediates (*OOH, *OO). Notably, a substantial fraction of enhanced catalytic activity is preserved for hours in the dark, maintaining ∼127% higher than the initial state after 3 h, highlighting its potential for efficient energy conversion under intermittent solar illumination.

Two-dimensional chiral covalent organic frameworks (2D-CCOFs) stand out as excellent candidates for chiral spintronic devices owing to their tailorable semiconducting structures and intrinsic chiral sites. However, two critical challenges currently hinder their development: first, the difficulty in synthesizing highly crystalline 2D-CCOF films and, second, the lack of reliable methods to construct stable 2D-CCOF-based spintronic devices. Herein, we successfully synthesized a 2D-CCOF film featuring a high crystallinity and excellent conductivity. In situ magnetic conductive-probe AFM (in situ mCP-AFM) characterization confirms that this 2D-CCOF exhibits excellent chiral-induced spin selectivity (CISS), with a spin polarization over 90% at room temperature. Using graphene as a blocking layer, we have successfully constructed stable half-spin valve devices based on the 2D-CCOF, which exhibit distinct chirality-dependent magnetoresistance. Graphene plays a key role in mitigating the detrimental effect of electrode deposition on the CCOF films. The excellent spin selectivity of 2D-CCOF opens up unprecedented opportunities for efficient control of electron spin and enables solid-state chiral spintronic devices.

The interaction between circularly polarized light (CPL) and chiral matter generates spin-polarized charge carriers; however, efficiently converting this microscopic spin imbalance into a macroscopic electrical signal remains a central challenge in CPL detection. Herein, we present an electrochemical CPL detection platform based on a metalated chiral covalent organic framework (CCOF), where CPL-induced spin polarization is coupled with the spin-selective oxygen evolution reaction (OER) to enable nonlinear transduction of spin polarization into an amplified electrical response. The nonlinear spin-dependent OER kinetics serves as an internal gain module that amplifies the electrical readout of spin imbalance, transforming CPL detection from a direct light-to-current conversion into a cascade process involving spin generation, nonlinear transduction of spin polarization, and current readout, resulting in a pronounced enhancement of the photocurrent anisotropy beyond that achievable in solid-state CPL detectors. Furthermore, systematic substitution of Co with heavier Ru and Re centers establishes a correlation among spin–orbit coupling (SOC) strength, microscopic chiroptical response (g_CD and P_CPL), and macroscopic device performance (G_Iph). This cascade spin generation-nonlinear electrochemical amplification strategy boosts the photocurrent anisotropy factor (G_Iph) to as high as 0.52, providing a rational approach for the systematic enhancement of CPL detection performance.

The crystallinity and stacking order of two-dimensional covalent organic frameworks (2D COFs) are critical to their physical properties and overall performance. However, direct molecular-resolution insight into the growth of layered 2D COFs remains elusive, particularly for imine-linked systems. Herein, we construct imine-linked bilayer 2D COFs at the solid-liquid interface, enabling time-dependent scanning tunneling microscopy (STM) visualization of interlayer growth. STM imaging revealed a layered growth mechanism involving defect-mediated nucleation, lattice-guided directional propagation, cross-defect growth, and oriented domain coalescence. This growth pathway gives rise to local order-on-disorder stacking associated with defect-induced registry variations. These findings provide direct molecular-level visualization of layered growth in imine-linked COFs and uncover a mechanistic origin of stacking disorder in bulk COFs.

Nowadays, most manufacturing memory devices are based on materials with electrical bistability (i. e., “0” and “1”) in response to an applied electric field. Memory devices with multilevel states are highly desired so as to produce high‐density and efficient memory devices. Herein, we report the first multichannel strategy to realize a ternary‐state memristor. We make use of the intrinsic sub‐nanometer channel of pillar[5]arene and nanometer channel of a two‐dimensional imine polymer to construct an active layer with multilevel channels for ternary memory devices. Low threshold voltage, long retention time, clearly distinguishable resistance states, high ON/OFF ratio (OFF/ON1/ON2=1 : 10 : 10³), and high ternary yield (75 %) were obtained. In addition, the flexible memory device based on 2DP_TPAZ+TAPB can maintain its stable ternary memory performance after being bent 500 times. The device also exhibits excellent thermal stability and can tolerate a temperature as high as 300 °C. It is envisioned that the results of this work will open up possibilities for multistate, flexible resistive memories with good thermal stability and low energy consumption, and broaden the application of pillar[n]arene.

Layered sodium metal oxide cathodes have much broader choice of transition metal elements than the Li counterparts. A reversible Cu^2+/3+ redox couple has recently been introduced in such Na cathodes. To study the role of Cu, here P2‐type layered Na_0.75Mn_0.6Fe_0.2(Cu_xNi_0.2‐x)O₂ compounds have been designed, synthesized and investigated. It shows the high initial capacity of 206 mAh/g and good capacity retention. Reversible oxygen redox activity is observed in our experiments. Our DFT calculations suggest that Cu can stabilize the oxygen redox by modifying the electronic structure together with Fe at high voltages. In addition, the strong P′2 transition observed at low voltages is induced by Jahn‐Teller active Cu²⁺ with two competing effects of enhanced Na ion diffusivity and reduced electronic conductivity.