Research

Overview

Our primary goal of research is to combine computational and experimental approaches to explore the electronic, electrochemical and catalytic properties of the nanomaterials, to develop the cost-effective route to synthesize and process advanced materials for biomedical, electronics, energy regeneration and storage applications.

A. Advanced Materials Synthesis and Processing

Developing advanced materials by cost-effective routes is the key step for the various applications in electronics, energy conversion and storage. We have initiated or participated in the synthesis AND PROCESSINGof various nanomaterials such as graphene (Z. Yan, J. Lin et al. ACS Nano 2012 6(10), 9110-9117;  Z. Yan, Y. Liu, J. Lin et al.  JACS 2013, 135 (29), 10755–10762) and graphene-CNTs (R.K. Paul,  Small 2010 6(20), 2309-2313), graphene-ZnO (J. Lin et al. Small ,2010 6(21), 2448-2452), vertically aligned graphene nanoribbons (C. Zhang, Z. Peng, J. Lin, et al., ACS Nano, 2013, 7 (6), 5151–5159), graphene quantum dots (R. Ye, C. Xiang, J. Lin et al., Nat. Commun. 2013, 4, 2943), VO2 nanowires (J. Lin et al.,  Nano Lett.20149, 5445-5451) and WS2 nanoribbons (J. Lin et al.,  Adv. Energy Mater. 2014, 4 (10), 1301875). Furthermore, nanomaterials can be produced in large scale, which extends their applications in additive manufacturing. The techniques involved in these projects include:

  • Chemical Vapor Deposition Synthesis (Vapor-Solid and Vapor-Liquid-Solid)
  • Colloidal Solution Synthesis
  • Electrochemical Anodization (Nanoporous Metal Oxides)
  • Electrochemical Deposition (Semiconducting Nanowires)
  • Laser processing
  • 3D printing

         

                         Z. Yan, J. Lin et al. ACS Nano 2012 6(10), 9110-9117       J. Lin, et al. Small 2010 6(21), 2448-2452

B. Computational Materials

Enabled by the tremendous advances in computational capability by supercomputers, computational materials science goes to a new stage of opening an unprecedented opportunity to design new materials with targeted properties. It breaks the traditional trial-error materials development loop of synthesis, processing, and characterizations. The opportunity is to provide a real-time feedback to this loop. By this way it will reduce the time from discovery to deployment of new materials by a factor of two, as projected by Materials Genome Initiative for Global Competitiveness (MGI) announced by white house in 2011. It is also strongly tied to advancement of American manufacturing capability. We will utilize and extend current theory and models of materials towards a paradigm shift, in which computational hardware and software, coupled with experimental data, enable to design, discover, and develop new advanced materials and structures. In turn, we will create new advanced, innovative technologies. Our recent publication on MD simulation of graphene materials synthesis from polymers without metal catalysts was a good starting point (Y. Dong, et al. Carbon, 2016).

C. Applications

C.1 Integrated Programmable Materials and Devices

Biological systems, such as the nastic plants, possess adaptive and predictable functions when exposed to various environmental stimuli (humidity, light, and touch), which results in dynamic morphology transformations governed by their compositions and anisotropic microstructures. The bio-mimicked shape-programmable systems have aroused interests in areas of smart textiles, micro-robotics, and metamaterials et al. Our research interest in this area is to synthesize and process novel materials to build a responsive and integrative systems. The goal is to understand their synthesis-processing-structure performance for application in biomedical areas.

C.2 Electronics and Optoelectronics

Electronics behavior differently when they are confined in low dimensions (1D and 2D) compared with the 3D bulk counterparts. Studying the electronics in the nanoscale paves the new route of developing next-generation electronics for applications in bioelectronics, photodetectors, transparent touch scree, memories and so on. Motivated by these applications we have studied the  interactions of DNA and graphene (J. Lin et al, Small2010, 6 (10), 1150-1155), demonstrated the potential applications of graphene for DNA biosensors (S. Guo, J. Lin et al., J.N.N. 2011 (6), 5258-5263). We have developed the transparent resistive switching memory based on SiOx and graphene (J. Yao*, J. Lin* et al., Nat. Commun., 2012, 3, 1101). This work has offered the possibility of providing the new functionality to the glass as it becomes the fundamental construction elements in modern buildings. We have reported addressable SiOx memory with 1D-1R architecture to solve the crosstalk problem in the crossbar devices (G. Wang, A. Lauchner, J. Lin et al., Adv. Mater. 2013, 25 (34), 4789-4793). We have studied the hydrogen diffusion in strong correlated VO2 nanowires ( J. Lin et al.,Nano Lett. 2014, 9, 5445-5451). Currently, we are working in the twoimensional layer transition metal dichalcogenides (LTMDs) such as MoS2, WSe2, SnS2, and SnSe2.

                                                 
                                                                                J. Yao*, J. Lin*, et al. Nat. Commun. 2012, 3, 1101

C.3 Energy Storage and Conversion

C.3.1 Supercapacitors

A supercapacitor, also called an ultracapacitor or an electrical double-layer capacitor (EDLC), is an energy storage device delivering high power, although it stores a lower energy density compared with rechargeable batteries. Thus, it is thought to bridge the gap between the conventional capacitors and batteries. It includes EDLCs, pseudocapacitors and hybrid capacitors. It can store much more charge because of the double layer formed at an electrolyte–electrode interphase when voltage is applied.
Our interest in supercapacitors is to explore the carbon nanomaterials for EDLC or transition metal oxides for pseudocapacitor (J. Lin et al., J.N.N. 2012, 12 (3), 1770-1775). As the demand for portable electronics increases, research in microscale or miniaturized devices is drawing much attention . Recently, we have successfully demonstrated the microsupercapacitors made from graphene-CNTs 3D hybrid materials (J. Lin et al. Nano Lett., 2013 13 (1), 72-78). Furthermore, we discovered that porous graphene materials can be produced and patterned using simple CO2 laser. The fabricated microsupercapacitors exhibit promising applications (J. Lin et al., Nat. Commun., 2014, accepted).

 
                                                            

                                                                                                                             J. Lin et al. Nano Letters, 2013 13 (1), 72-78

                                                                                   

                                                                                                                              J. Lin et al. Nature Communications, 2014, accepted

C.3.2 Rechargeable Batteries 

LIBs, the most important devices among the catalog of rechargeable batteries, have drawn tremendous attention from both academics and industry. Development of new anode materials with high specific capacity for LIBs is a key step forwarded for applications to large-scale energy storage units such as electrical vehicles. Among the candidates replacing current commercial graphite with only capacity of 372 mAh/g the metal oxides such as iron oxide and tin oxide have been intensively investigated because of their high capacity and low cost. However,the enormous volume expansion and structural changes during repeated lithium insertion/desertion causes significant capacity fading during cycling. Making the materials in the nanoscale mitigates the effect. Another approach is to integrate the oxides with buffering and conductive additives. Based on these strategies, we have developed graphene nanoribbons with SnO2 nanoparticles (J. Lin et al., ACS Nano 2013,  7 (7), 6001–6006) and Fe2O3 nanoparticles (J. Lin et al., Adv. Funct. Mater. 2013, 24(14), 2044-2048). Not only the high capacity of the anodes were achieved, but also the excellent cycling performance was realized. Rechargeable batteries beyond lithium ion are our group’s major interest now. They include magnesium, calcium, and aluminium ion batteries.

                                                     

                                                                                                                                   J. Lin et al. ACS Nano 2013, 7 (7), 6001-6006

C.3.3 Catalysis for Chemical Fuels

The research in the clean fuel such as H2 has drawn much attention due to the concerns of the greenhouse gas emission such as CO2 from burning the traditional carbon-based fuels. Hydrogen evolution reaction (HER) via electrocatalysis is one of the paramount ways to obtain H2, which can be realized from water by applying potential over thermodynamic limit of HER. Achieving the HER efficiently at low overpotential provides a promising route to the clean energy. Currently, platinum is widely applied for this purpose because of its most electrocatalytic activity and electrochemically stability. Replacement of this previous and expensive metal with abundant and cost-effective materials has aroused extensive interest and motivated various studies. Recently, progress has been realized by using MoS2 and its derivatives. The theoretic and experimental studies have suggested that HER activity of MoS2 has strong correlation with its number of the exposed edges rather than its inert basal plane (1000). Thus we developed some MoS2-like two dimensional materials. For the first demonstration, the HER activity of WSNanoribbons with abundant exposed edges unzipped from WSNTs (J. Lin et al.,  Adv. Energy Mater. 2014, 4(10), 1301875). Through novel processing technique, we in-situ synthesize and pattern catalysts for on-chip applications (H. Deng, et al. J. Mater. Chem. A, 2016).

 
                                                 
                                                                                                                                                                  J. Lin et al., Advanced Energy Materials 2014, 4(10), 1301875