My research specialty is design and synthesis of functional materials for sustainable energy-associated applications. Specifically, my research projects can be divided into the following three categories:
1. [Primary] Carbonaceous materials for supercapacitors Supercapacitors, similar as lithium-ion batteries, are charge storage devices capable of charging and discharging at much faster rates than conventional batteries. They are using in conjunction with solar cells for electricity storage, and lithium-ion batteries inside of electric vehicles. Operations of lifts, emergency doors, back-up power stations and race cars depend on supercapacitors in some cases. Below are two videos showing laboratory designed supercapacitors can power certain electronics.
My research projects deal mainly with carbon-based materials and are categorized into the subsequent three aspects:
Light-weight supporting substrates for pseudo-capacitors. My research focuses on development of light-weight carbon-based substrates for pseudo-capacitors that are alternative to the conventional metal-based substrates. These substrates have improved the gravimetric energy and power densities of pseudo-capacitors. One representative research work is the 3D graphene scaffold that can serve as an excellent light-weight scaffold for manganese dioxide [Nano Lett., 15, 3189-3194 (2015)].
Active materials for charge storage. Carbon itself can store charges via formation of electrical double layer. Highly porous carbons with ultrahigh surface area are desirable as supercapacitor electrodes. My research focuses on designing and synthesis of hierarchical porous carbons for supercapcitor electrodes. Representative research works include the 3D-printed graphene aerogel [(Nano Lett., 16, 3448-3456 (2016)] and the hierarchical porous carbon foam derived from chitosan biopolymer [Nano Res., 9, 2875-2888 (2016) and Nano Lett., 17, 3097-3104 (2017)].
Collaborators: Dr. Marcus A. Worsley (Staff Scientist in Lawrence Livermore National Lab); Dr. Cheng Zhu (Staff Scientist in Lawrence Livermore National Lab); Prof. Xihong Lu (Associate Professor in Sun Yat-sen University, Guangdong, China); Dr. Teng Zhai (Assistant Professor in Nanjing University of Science and Technology, Nanjing, China); Prof. Xiaoxia Liu (Professor in Northeastern University, Shenyang, China); Prof. Feng Zhang (Associate Professor in Yancheng Institute of Technology, Yancheng, China)
2. Anode materials for microbial fuel cells Microbial fuel cells are special fuel cells which employ bacteria to convert organic matters or pollutants to energy, simultaneously yield methane gas, hydrogen gas, or liquid fuels as byproducts. They represent promising devices for water treatment and power generation. They have been already incorporated in some wastewater treatment plants and brewery companies. In collaboration with Yang Yang at the Chongqing University, we seek to explore and synthesize novel carbonaceous architectures as electrodes for bacteria to colonize on. A representative work is the nitrogen-doped graphene aerogel which enabled large-density bacterial colonization throughout the aerogel and significantly improved the performance of microbial fuel cells [Adv. Sci., 3, 1600097 (2016)]. Collaborator: Dr. Yang Yang (Assistant Professor, Northwestern Polytechnical University, China)
3. Semiconductors for solar-driven/photo-electrochemical water splitting Water splitting using solar light and semiconductors is an environmentally benign way to obtain the hydrogen gas, an emission-free sustainable fuel. Solar harvesting represents the first step toward the solar water splitting. We aim at obtaining semi-conductors that can achieve state-of-the-art performance as well as addressing fundamental limitations of certain semiconductors, such as hematite and titania. For example, we recently discovered that the titanium dioxide, which is believed to be a very stable photo-anode, experienced an apparent decay in photo-current after a prolonged working duration. The instability is believed to be caused by photo-hole corrosion. Such instability can be alleviated through addition of hole scavengers, such as methane into electrolytes [Nano Lett., 15, 7051-7057 (2015)]. Collaborators: Prof. Xihong Lu (Associate Professor in Sun Yat-sen University, Guangzhou, China); Prof. Gongming Wang (Professor in University of Science and Technology, China, Hefei, China)
4. Heteroatom-doped Carbon-based Materials As Efficient Catalysts Actively exploration of carbon materials doped with oxygen, nitrogen, sulfur etc. with hierarchical porous structures and carbon-functional composites for a variety of catalytic applications: oxygen reduction reaction, carbon dioxide reduction, sulfur removal, hydrogen evolution reaction and oxygen evolution reaction.
Collaborators: Prof. Gengfeng Zheng (Associate Professor in Fudan University, Shanghai, China); Prof. Gongming Wang (Professor in University of Science and Technology, China, Hefei, China); Prof. Scott Oliver (Professor in University of California, Santa Cruz).