Qiang Gao

Oak Ridge National Laboratory | ORNL · Center for Nanophase Materials Sciences

This study investigates the large voltage range of symmetric carbon/carbon capacitors in environmentally friendly aqueous lithium sulfate electrolyte. A high over-potential related to the hydrogen sorption mechanism at the negative electrode contributes usefully to enhance the operating voltage up to 1.9 V with an excellent stability during 10 000...

Oxygen evolution and catalyst corrosion were studied side by side for electrodeposited MnOx catalysts. Measurements using a combination of electrochemical flow cell, atomic absorption spectroscopy, and rotating ring disk electrode reveal a high sensitivity of oxygen evolution and of manganese oxide corrosion toward the presence of ions (alkali-meta...

Two-dimensional materials, such as MXenes, are attractive candidates for energy storage and electrochemical actuators due to their high volume changes upon ion intercalation. Of special interest for boosting energy storage is the intercalation of multivalent ions such as Mg(2+), which suffers from sluggish intercalation and transport kinetics due t...

Enhancing the energy stored and power delivered by layered materials relies strongly on improved understanding of the intricate interplay of electrolyte ions, solvents, and electrode interactions as well as the role of confinement. Here we report a highly integrated study with multiscale theory/modelling and experiments to track the intercalation o...

A novel activation method involving hydrothermal carbonization (HTC) and a pressure-induced low temperature oxidation has been demonstrated for cellulose derived HTC char by using hydrogen peroxide as an active di-oxygen source. The optimized porosity versus gravimetric capacitance results from cellulose derived HTC char synthesized at 220 oC. Almo...

Electrochemical energy storage is the key enabling component of electric vehicles and solar‐/wind‐based energy technologies. The enhancement of energy stored requires the detailed understanding of charge storage mechanisms and local electrochemical and electromechanical phenomena over a variety of length scales from atoms to full cells. Classical e...

In article number 1901751, Mengmeng Cui, Amit K. Naskar, and co‐workers use lignin oligomers as renewable surfactant particles that form a 2D surfactant sheet via spontaneous unfolding at polar‐nonpolar liquid interface‐just like a cast net thrown onto the interface. Due to the significant interfacial activity, these amphiphilic molecules exhibit u...

Wrapping a 3D object with a 2D sheet is not uncommon, but the wrapping behavior becomes complex and interesting when the sheet is bestowed with strong interfacial activities. Amphiphilic lignin macromolecules, isolated from biomass, form a scalable thin surfactant sheet at an oil/water interface through the interfacial jamming process. The process...

Cobalt (Co) nanoparticles anchored porous N-doped carbon nanosheets ([email protected]) were fabricated using a facile one-pot pyrolysis route and tested as high-performance cathode catalysts for Li-O2 batteries. The hierarchical structure was made of cobalt nanoparticles distributed in the crumpled porous carbon nanosheets. Uniformly distributed a...

TiO2 nanorod (NR) array for perovskite solar cells (PSCs) has attached great importance due to superb power conversion efficiency (PCE) compared to traditional mesoporous TiO2 film. A TiO2 compact layer for the growth of TiO2 NR array via spin-coating cannot meet the requirements for efficient NR based PSCs. Herein we have developed and demonstrate...

Hydrogen production from photoelectrochemical (PEC) water splitting using semiconductor photocatalysts has attracted great attentions to realize clean and renewable energy from solar energy. A visible-light-response WO3 with a long hole diffusion length (~150 nm) and good electron mobility (~12 cm2 V-1 s-1) makes it suitable as the photoanode. Howe...

For an effective hydrogen generation with a remarkable durability, the grown carbon nanotubes (CNTs) on the Ni nanofibers and their post hydroxylation treatment engendered active Ni nanofiber catalysts an efficient...

The presence of structural water leads to a transition of energy storage mechanism in tungsten oxide from battery-type intercalation (bulk diffusion limited) to pseudocapacitance (interface kinetics limited). In this study, we demonstrate that the energy storage mechanisms are linked to the material’s mechanical response to the intercalation proces...

Efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated MoS2xSe2(1-x) well-dispersed spherical nanocatalysts. The resulting catalysts present a high...

Neutral aqueous alkali sulfate has shown great interests for developing environmentally friendly high voltage and high energy supercapacitors. This work focuses on systematically investigating the properties of symmetric carbon/carbon supercapacitors in neutral aqueous alkali sulfates. At room temperature, the largest power and energy density were...

High absorption capacity and broad absorption bandwidth electromagnetic wave (EMW) absorption materials (namely, EMW absorbers) are highly desirable due to the interference with electronics and harms on human beings’ health. In search for rational design on nanostructured absorbers, we have synthesized and demonstrated the rod-shape composites with...

Nanocomposites with a well-defined sandwich-like nanostructure were prepared via in situ growing NiCo-layered double hydroxide nanosheets with tunable Ni/Co ratios on the reduced graphene oxide (rGO). Electrochemical impedance spectra and N2 adsorption/desorption isotherms confirmed that these sandwich nanostructures effectively promoted the charge...

Silicon carbon (Si/C) materials are promising anode candidates for high performance lithium ion batteries (LIBs). However, serious volume expansion and solid electrolyte interface formation limited their actual capacity during lithiation and delithiation. In the present study, an innovative and low-cost synthetic approach was developed for synthesi...

2D transition metal dichalcogenides with a formula MoX2 (X=S or Se) have been explored as promising earth‐abundant catalysts for hydrogen evolution reaction (HER), especially those with 1T phases. Theoretical calculations and experiments have indicated that optimal catalytic performance can be achieved by regulating the atomic ratio of S and Se in...

Chemical energy conversion/storage through water splitting for hydrogen production has been recognized as the ideal solution to the transient nature of renewable energy sources. Solid polymer electrolyte (SPE) water electrolysis is one of the most practical ways to produce pure H2. Electrocatalysts are key materials in the SPE water electrolysis. A...

The presence of structural water in tungsten oxides leads to a transition in the energy storage mechanism from battery-type intercalation (limited by solid state diffusion) to pseudocapacitance (limited by surface kinetics). Here, we demonstrate that these electrochemical mechanisms are linked to the mechanical response of the materials during inte...

The ability of structural water to act as an ‘internal electrolyte’ for ion transport within transition metal oxides is an intriguing concept for improving the kinetics of energy storage, particularly to enable high volumetric capacitance. Crystalline tungsten oxide dihydrate (WO 3 ·2H 2 O) is a model compound to investigate whether interlayer stru...

In the past decades, electrochemical capacitors (supercapacitors) have drawn considerable attention for applications in portable electronics, grid and transportation systems due to their rapid power delivery and an almost unlimited cycle life. In search for new materials with higher electrochemical performance, two dimensional (2D) transition metal...

Iridium oxide is one of the most important catalysts for water oxidation. Yet, the atomic structure of this catalyst remains unknown. We have studied anodically grown iridium oxide catalyst films using Raman Spectroscopy. Besides, deuteration and O18 substitution experiments, theoretical models were also constructed using density functional theory...

The surface chemistry of nanocarbon support can tailor chemical properties of precious metal nanoparticle/nanocarbon hybrid catalyst in heterogeneous reactions. We report on modified reduced graphene oxide (rGO) support with ionic liquid-derived carbonaceous surface for palladium nanoparticle (Pd NPs) decoration and their actions in different heter...

Non noble metal "earth abundant" electrocatalysts will significantly reduce the costs and make it possible to use electrochemical water splitting (electrolysis) on a very large scale. Non noble metal catalysts can be an effective replacement even if their electrochemical activities are a fraction of their noble metal counterparts. If these catalyst...

Water oxidation is one of the biggest challenges towards establishing a sustainable energy economy based on renewable energy. Non noble metal electrocatalysts can significantly reduce the costs and make usage of electrochemical water splitting on a large scale possible. Those metal oxide catalysts can be an effective replacement even if their elect...

A polymeric activated carbon (PAC) was synthesized from the carbonization of a resorcinol–formaldehyde resin with KOH served as an activation agent. The nitrogen adsorption–desorption at 77K, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared PAC. Compared with the commercial activated carbon (...

To improve electrochemical properties of activated carbon (AC), a commercial AC was modified by means of soaking in manganese nitrate solution and subsequent pyrolysis. Nitrogen adsorption at 77 K, SEM, and XRD were used to study the surface area, porosity, profile of modified AC, and the crystal structure of deposited manganese oxides. The perform...

A commercial activated carbon was modified by surface treatment using three chemicals, nitric acid, hydrogen peroxide, and ammonia, respectively. The modified carbons were characterized by N2 adsorption-desorption isotherms and FTIR spectroscopy. The resultant carbon electrode-based electric double-layer capacitors (EDLCs) were assembled with 6 mol...