Scalable synthesis of gyroid-inspired freestanding three-dimensional graphene architectures

Machine learning unifies flexibility and efficiency of spinodal structure generation for stochastic biomaterial design

Porous biomaterials design for bone repair is still largely limited to regular structures (e.g. rod-based lattices), due to their easy parameterization and high controllability. The capability of designing stochastic structure can redefine the boundary of our explorable structure-property space for synthesizing next-generation biomaterials. We hereby propose a convolutional neural network (CNN) approach for efficient generation and design of spinodal structure-an intriguing structure with stochastic yet interconnected, smooth, and constant pore channel conducive to bio-transport. Our CNN-based approach simultaneously possesses the tremendous flexibility of physics-based model in generating various spinodal structures (e.g. periodic, anisotropic, gradient, and arbitrarily large ones) and comparable computational efficiency to mathematical approximation model. We thus successfully design spinodal bone structures with target anisotropic elasticity via high-throughput screening, and directly generate large spinodal orthopedic implants with desired gradient porosity. This work significantly advances stochastic biomaterials development by offering an optimal solution to spinodal structure generation and design.

Eco-Friendly Approach for Graphene Oxide Synthesis by Modified Hummers Method

The aim of this study is to produce graphene oxide using a modified Hummers method without using sodium nitrate. This modification eliminates the production of toxic gases. Two drying temperatures, 60 °C and 90 °C, were used. Material was characterized by X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and Scanning Electron Microscopy. FTIR study shows various functional groups such as hydroxyl, carboxyl and carbonyl. The XRD results show that the space between the layers of GO60 is slightly larger than that for GO90. SEM images show a homogeneous network of graphene oxide layers of ≈6 to ≈9 nm. The procedure described has an environmentally friendly approach.

Influence of Magnetic Moment on Single Atom Catalytic Activation Energy Barriers

Design of the molecular environment of single atom catalysts (SAC) is promising for achieving high catalytic activity without expensive and scarce platinum-group metals (PGM). We utilize a first principles approach to examine how the spin state of the SAC and reactants can affect catalytic energy barriers of V, Fe, Mo, and Ta on two different graphene defects with differing magnetic moments. Spin polarized projected density of states and climbing image nudged elastic band calculations demonstrate relatively lower activation energy barriers for systems with higher spin state asymmetry near the Fermi energy; CO oxidation on Ta and V SAC have decreases in activation barrier energies of 27% and 44%, respectively.

Graphic Abstract

Ultra-low-density digitally architected carbon with a strutted tube-in-tube structure

Porous materials with engineered stretching-dominated lattice designs, which offer attractive mechanical properties with ultra-light weight and large surface area for wide-ranging applications, have recently achieved near-ideal linear scaling between stiffness and density. Here, rather than optimizing the microlattice topology, we explore a different approach to strengthen low-density structural materials by designing tube-in-tube beam structures. We develop a process to transform fully dense, three-dimensional printed polymeric beams into graphitic carbon hollow tube-in-tube sandwich morphologies, where, similar to grass stems, the inner and outer tubes are connected through a network of struts. Compression tests and computational modelling show that this change in beam morphology dramatically slows down the decrease in stiffness with decreasing density. In situ pillar compression experiments further demonstrate large deformation recovery after 30-50% compression and high specific damping merit index. Our strutted tube-in-tube design opens up the space and realizes highly desirable high modulus-low density and high modulus-high damping material structures.

Self-Assembly Lightweight Honeycomb-Like Prussian Blue Analogue on Cu Foam for Lithium Metal Anode

As a next-generation anode material for lithium batteries, Li metal anode suffers from inherent drawbacks such as infinite volume expansion and uneven Li plating/stripping. Herein, we propose a lightweight lithiophilic Prussian blue analogue (PBA) with honeycomb-like structure on Cu foam by self-assembly method to address these issues. The unique honeycomb-like architecture could provide enlarged surface areas and abundant deposition sites for homogenizing Li⁺ flux during Li plating. Consequently, the elaborate PBA-decorated Cu foam current collector enables long-term (1800 h) reversible plating/stripping behavior and an observably improved Coulombic efficiency (98.3% after 350 cycles). The concept of the direct self-assembly synthesis method on metal foam provides new insights into the design of a lightweight 3-dimensional current collector for Li metal anode.

Comparison of Fused Deposition Modeling and Color Jet 3D Printing Technologies for the Printing of Mathematical Geometries

Many mathematical geometries act as an optimal structure for functional applications and have always been an area of interest in the research field. Their topology offers properties which are crucial and can be used effectively in various domains. Apart from that, some have a resemblance to naturally occurring compounds which can help us to study their different transformations and behavior. In this paper, we present two such geometries, first, gyroid, which is an iso-minimal surface and second a three-crossing knot, also known as trefoil knot. The structure of gyroid makes it unique and is considered suitable in developing energy-absorbing, structural and lightweight applications. Similarly, some types of knots resemble the DNA structure and have found use in molecular chemistry. This paper discusses different application areas of these geometries. Further, this paper presents modeling and printing by using fused deposition modeling (FDM) and color jet printing (CJP). Comparative analysis has been done by considering various parameters. This paper discusses the potential of these two rapid prototyping technologies and their suitability for specific printing applications.