Ultrathin two-dimensional metal–organic frameworks (MOFs) have convincing performances in energy storage, which can be put down to their accessible active sites with rapid charge transfer. Herein, NiCo-layered double hydroxide (LDH) nanosheet arrays are used as self-sacrificial templates to in situ fabricate ultrathin NiCo-MOF nanosheet arrays on Ni foam (NS/NF) by using organic ligands without adding metal sources. Two ultrathin MOF nanosheets with different ligands, terephthalate (BDC) and 2-aminoterephthalate (NH2-BDC), are synthesized, characterized, and discussed in detail. Specifically, NiCo-NH2-BDC-MOF NS/NF exhibits the best electrochemical performance as a battery-type electrode for supercapacitors, achieves an areal capacitance of 12.13 F cm–2 at a current density of 2 mA cm–2, and retains the original capacitance of 73.08 % after 5000 cycles at a current density of 50 mA cm–2. Furthermore, when NiCo-NH2-BDC-MOF NS/NF is assembled with activated carbon (AC) to form an asymmetric supercapacitor (ASC), an energy density of 0.81 mWh cm–2 can be provided at a power density of 1.60 mW cm–2. These results offer an effective and controllable synthetic strategy to in situ prepare ultrathin MOF nanosheet arrays with different ligands and metal ions from LDH precursors.

Brain-inspired intelligent systems demand diverse neuromorphic devices beyond simple functionalities. Merging biomimetic sensing with weight-updating capabilities in artificial synaptic devices represents one of the key research focuses. Here, we report a multiresponsive synapse device that integrates synaptic and optical-sensing functions. The device adopts vertically stacked graphene/h-BN/WSe2 heterostructures, including an ultrahigh-mobility readout layer, a weight-control layer, and a dual-stimuli-responsive layer. The unique structure endows synapse devices with excellent synaptic plasticity, short response time (3 μs), and excellent optical responsivity (105 A/W). To demonstrate the application in neuromorphic computing, handwritten digit recognition was simulated based on an unsupervised spiking neural network (SNN) with a precision of 90.89%, well comparable with the state-of-the-art results. Furthermore, multiterminal neuromorphic devices are demonstrated to mimic dendritic integration and photoswitching logic. Different from other synaptic devices, the research work validates multifunctional integration in synaptic devices, supporting the potential fusion of sensing and self-learning in neuromorphic networks.

A core–shell structure composite material consisting of a conductive polymer and 2D conductive metal–organic frameworks (CMOFs) was assembled by hydrothermal methods. The use of polypyrrole (PPy) as a backbone effectively prevents the aggregation of CMOFs. Its own hollow structure provides better conductivity while shortening the ion diffusion pathway. Benefiting from the rational structural design, the performance of 572.2 F g–1 is demonstrated by the core–shell PPy@NiCo-CAT electrode. In addition, we incorporated the material into the hybrid supercapacitor (HSC) and verified its excellent energy density and lifetime. Furthermore, 12 light-emitting diodes (LEDs) can be illuminated by two HSCs connected in series. The strategy of compounding conductive polymers with 2D CMOFs provides additional options for developing electrode materials for high-performance HSC devices.

The amino-functionalized bimetal NH2-NiCo-MOF nanosheet array is first fabricated on Ni foam substrates and then controllably transformed into oxygen vacancy bimetal oxide arrays by simply thermal annealing in air. This NiCo-based oxide array (Ni x Co3–x O4/NF) achieves high capacitance (2484 F g–1 at 1 A g–1), excellent rate performance (91.4%), and long cycling life when assessed as promising electrode material for supercapacitors. Notably, the existing oxygen vacancy in Ni x Co3–x O4 promotes the electrochemical performance of Ni x Co3–x O4/NF due to the enhancement of electrical conductivity and capture capability for OH–. In addition, the assembled asymmetric supercapacitor (ASC) device exhibits an excellent energy density of 39.3 W h kg–1 at a power density of 800.2 W kg–1, which still remains 32.2 W h kg–1 even at a high power density of 7994.5 W kg–1. Furthermore, a light-emitting diode can be lightened for more than 6 min, demonstrating a great potential for practical application of ASC devices. This work knocks on the door of a feasible strategy for designing and synthesizing 2D metal oxide nanosheet arrays with excellent electrochemical properties.

Reasonable design of electrodes with well-defined nanostructure is the central aspects in the practical application of high-performance supercapacitors. Herein, hollow tube@sheets NiCo2S4 core-shell nanoarrays are rationally constructed to free-standing electrode...