Stacked Two-Dimensional MXene Composites for an Energy-Efficient Memory and Digital Comparator.

Two-dimensional MXene has enormous potential for application in industry and academia owing to its surface hydrophilicity and excellent electrochemical properties. However, the application of MXene in optoelectronic memory and logical computing is still facing challenges. In this study, an optoelectronic resistive random access memory (RRAM) based on silver nanoparticles (Ag NPs)@MXene-TiO2 nanosheets (AMT) was prepared through a low-cost and facile hydrothermal oxidation process. The fabricated device exhibited a typical bipolar switching behavior and controllable SET voltage. Furthermore, we successfully demonstrated a 4-bit in-memory digital comparator with AMT RRAMs, which can replace five logic gates in a traditional approach. The AMT-based digital comparator may open the door for future integrated functions and applications in optoelectronic data storage and simplify the complex logic operations.

Near-Infrared Artificial Synapses for Artificial Sensory Neuron System.

The computing based on artificial neuron network is expected to break through the von Neumann bottleneck of traditional computer, and to greatly improve the computing efficiency, displaying a broad prospect in the application of artificial visual system. In the specific structural layout, it is a common method to connect the discrete photodetector with the artificial neuron in series, which enhances the complexity of signal recognition, conversion and storage. In this work, organic small molecule IR-780 iodide is inserted into the memory device as both the charge trapping layer and near-infrared (NIR) photoresponsive film. Through electrical and optical regulation, artificial synaptic functions including short-term plasticity, long-term plasticity, and spike rate dependence are realized. In the established artificial sensory neuron system, NIR optical pulses can significantly improve the spiking rate. Moreover, the spiking neural networks are further constructed by simulation for handwritten digit classification. This research may contribute to the development of light driven neural robots, optical signal encryption, and neural computing.

Fabrication and characterization of capric acid/reduced graphene oxide decorated diatomite composite phase change materials for solar energy storage.

In this paper, diatomite-based composite phase change materials (DI-based CPCMs) were fabricated by the vacuum impregnation of capric acid (CA) into reduced graphene oxide decorated diatomite (rGO-DI). In the DI-based CPCMs, DI was used as the supporting material, which was first purified by thermal treatment and alkali treatment, to improve the adsorption capacity of the PCM, rGO was used to decorate the DI to improve the thermal conductivity of CPCMs. The rGO-DI could retain CA at the weight fraction of 60% without leakage. The maximum melting and freezing enthalpy of CA/rGO-DI-2 reached 106.2 J g-1 and 108.6 J g-1, respectively, and its thermal conductivity was up to 0.5226 W m-1 · K, 260.4% and 81.3% higher than pure CA and CA/DI, respectively. The CPCMs have good thermal reliability and thermal stability, and there was no chemical reaction between CA and rGO-DI. The CPCMs maintained thermal properties after 200 melting-freezing cycles. Finally, the CPCMs have potential for application in solar energy storage systems.

Fabrication and thermal properties of tetradecanol/graphene aerogel form-stable composite phase change materials.

In this study, tetradecanol/graphene aerogel form-stable composite phase change materials were prepared by physical absorption. Two kinds of graphene aerogels were prepared using vitamin C and ethylenediamine to enhance the thermal conductivity of tetradecanol and prevent its leakage during phase transition. The form-stable composite phase change material exhibited excellent thermal energy storage capacity. The latent heat of the tetradecanol/graphene aerogel composite phase change materials with 5 wt.% graphene aerogel was similar to the theoretical latent heat of pure tetradecanol. The thermal conductivity of the tetradecanol/graphene aerogel composite phase change material improved gradually as the graphene aerogel content increased. The prepared tetradecanol/graphene aerogel composite phase change materials exhibited good thermal reliability and thermal stability, and no chemical reaction occurred between tetradecanol and the graphene aerogel. In addition, the latent heat and thermal conductivity of the tetradecanol/ethylenediamine-graphene aerogel composites were higher than those of tetradecanol/vitamin C-graphene aerogel composites, and the flexible shape of the ethylenediamine-graphene aerogel is suitable for application of the tetradecanol/ethylenediamine-graphene aerogel composite.