Gaixia Zhang - Academia.edu (original) (raw)

Papers by Gaixia Zhang

Molecules

High-performance electrocatalysts are critical to support emerging electrochemical energy storage... more High-performance electrocatalysts are critical to support emerging electrochemical energy storage and conversion technologies. Graphite-derived materials, including fullerenes, carbon nanotubes, and graphene, have been recognized as promising electrocatalysts and electrocatalyst supports for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR). Effective modification/functionalization of graphite-derived materials can promote higher electrocatalytic activity, stability, and durability. In this review, the mechanisms and evaluation parameters for the above-outlined electrochemical reactions are introduced first. Then, we emphasize the preparation methods for graphite-derived materials and modification strategies. We further highlight the importance of the structural changes of modified graphite-derived materials on electrocatalytic activity and stability. Finally, future directions and p...

Nano-Micro Letters

Highlights Three-dimensional (3D) core‐shell heterostructured NixSy@MnOxHy nanorods grown on nick... more Highlights Three-dimensional (3D) core‐shell heterostructured NixSy@MnOxHy nanorods grown on nickel foam (NixSy@MnOxHy/NF) were successfully fabricated via a simple hydrothermal reaction and a subsequent electrodeposition process. The fabricated NixSy@MnOxHy/NF shows outstanding bifunctional activity and stability for hydrogen evolution reaction and oxygen evolution reaction, as well as overall‐water‐splitting performance. The main origins are the interface engineering of NixSy@MnOxHy, the shell‐protection characteristic of MnOxHy, and the 3D open nanorod structure, which remarkably endow the electrocatalyst with high activity and stability. Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-prote...

Nanomaterials

Developing cheap and earth-abundant electrocatalysts with high activity and stability for oxygen ... more Developing cheap and earth-abundant electrocatalysts with high activity and stability for oxygen reduction reactions (ORRs) is highly desired for the commercial implementation of fuel cells and metal-air batteries. Tremendous efforts have been made on doped-graphene catalysts. However, the progress of phosphorus-doped graphene (P-graphene) for ORRs has rarely been summarized until now. This review focuses on the recent development of P-graphene-based materials, including the various synthesis methods, ORR performance, and ORR mechanism. The applications of single phosphorus atom-doped graphene, phosphorus, nitrogen-codoped graphene (P, N-graphene), as well as phosphorus, multi-atoms codoped graphene (P, X-graphene) as catalysts, supporting materials, and coating materials for ORR are discussed thoroughly. Additionally, the current issues and perspectives for the development of P-graphene materials are proposed.

Nano-Micro Letters, 2021

The electroreduction reaction of CO2 (ECO2RR) requires high-performance catalysts to convert CO2 ... more The electroreduction reaction of CO2 (ECO2RR) requires high-performance catalysts to convert CO2 into useful chemicals. Transition metal-based atomically dispersed catalysts are promising for the high selectivity and activity in ECO2RR. This work presents a series of atomically dispersed Co, Fe bimetallic catalysts by carbonizing the Fe-introduced Co-zeolitic-imidazolate-framework (C–Fe–Co–ZIF) for the syngas generation from ECO2RR. The synergistic effect of the bimetallic catalyst promotes CO production. Compared to the pure C–Co–ZIF, C–Fe–Co–ZIF facilitates CO production with a CO Faradaic efficiency (FE) boost of 10%, with optimal FECO of 51.9%, FEH2 of 42.4% at − 0.55 V, and CO current density of 8.0 mA cm−2 at − 0.7 V versus reversible hydrogen electrode (RHE). The H2/CO ratio is tunable from 0.8 to 4.2 in a wide potential window of − 0.35 to − 0.8 V versus RHE. The total FECO+H2 maintains as high as 93% over 10 h. The proper adding amount of Fe could increase the number of act...

Automotive Innovation, 2021

Proton exchange membrane (PEM) fuel cells have gained increasing interest from academia and indus... more Proton exchange membrane (PEM) fuel cells have gained increasing interest from academia and industry, due to its remarkable advantages including high efficiency, high energy density, high power density, and fast refueling, also because of the urgent demand for clean and renewable energy. One of the biggest challenges for PEM fuel cell technology is the high cost, attributed to the use of precious platinum group metals (PGM), e.g., Pt, particularly at cathodes where sluggish oxygen reduction reaction takes place. Two primary ways have been paved to address this cost challenge: one named low-loading PGM-based catalysts and another one is non-precious metal-based or PGM-free catalysts. Particularly for the PGM-free catalysts, tremendous efforts have been made to improve the performance and durability—milestones have been achieved in the corresponding PEM fuel cells. Even though the current status is still far from meeting the expectations. More efforts are thus required to further rese...

Advanced Energy Materials, 2020

existing energy supply systems mainly based on fossil fuels, the performance of the clean energy ... more existing energy supply systems mainly based on fossil fuels, the performance of the clean energy (conversion and storage) devices/systems has to be significantly improved. The electrochemical energy conversion and storage usually involves many intricate chemical reactions and physical interactions at the surface and inside of electrodes/electrolytes, and the kinetics and transport behaviors of different carriers (e.g., electrons, holes, ions, molecules) are closely associated with the materials selected for electrodes as well as the structures of electrodes. To this point, material design and structure design for electrodes have been the research focuses for improving the electrochemical performance of energy conversion and storage, which both have gained high attention from academia and industry. Along with researches for finding advanced electrode materials, much recent research efforts have been made for electrode structure design and engineering, especially when traditional macro-scale structured electrodes are showing limitations of achieving satisfying performance for energy conversion and storage. Among these efforts, electrode nanostructuring has been demonstrated as a promising way for realizing highperformance electrochemical energy conversion and storage, which attributes the distinct features of nanostructured materials differing from their bulk material counterparts. The high surface-to-volume ratios of nanostructures give large electrochemical surface areas with much more exposed atoms and hence improve the performance per unit electrode area and/or Electrochemical energy conversion and storage play crucial roles in meeting the increasing demand for renewable, portable, and affordable power supplies for society. The rapid development of nanostructured materials provides an alternative route by virtue of their unique and promising effects emerging at nanoscale. In addition to finding advanced materials, structure design and engineering of electrodes improves the electrochemical performance and the resultant commercial competitivity. Regarding the structural engineering, controlling the geometrical parameters (i.e., size, shape, heteroarchitecture, and spatial arrangement) of nanostructures and thus forming well-defined nanostructure (WDN) electrodes have been the central aspects of investigations and practical applications. This review discusses the fundamental aspects and concept of WDNs for energy conversion and storage, with a strong emphasis on illuminating the relationship between the structural characteristics and the resultant electrochemical superiorities. Key strategies for actualizing well-defined features in nanostructures are summarized. Electrocatalysis and photoelectrocatalysis (for energy conversion) as well as metal-ion batteries and supercapacitors (for energy storage) are selected to illustrate the superiorities of WDNs in electrochemical reactions and charge carrier transportation. Finally, conclusions and perspectives regarding future research, development, and applications of WDNs are discussed.

ACS Applied Materials & Interfaces, 2020

Highly active catalyst for the hydrogen oxidation/evolution and reactions (HOR and HER) plays an ... more Highly active catalyst for the hydrogen oxidation/evolution and reactions (HOR and HER) plays an essential role for the water to hydrogen reversible conversion. Currently, increasing attention has been concentrated on developing low-cost, highactivity, and log-life catalytic materials, especially for acid media due to the promise of proton exchange membrane (PEM) based electrolyzers and polymer electrolyte fuel cells. Although non-precious metal phosphides (NPMPs) catalysts has been widespread researched, their electrocatalytic activities towards HER still not satisfied compared with Pt catalysts. Herein, a series of precious metal phosphides (PMPs) supported on graphene (rGO) including IrP 2-rGO, Rh 2 P-rGO, RuP-rGO and Pd 3 P-rGO are prepared by a simple, facile, eco-friendly and scalable approach. As an example, the resultant IrP 2-rGO displays better HER electrocatalytic performance and longer durability than the benchmark materials of commercial Pt/C under acidic, neutral and basic electrolytes. To attain a current density of 10 milliamperes per square centimeter (mA cm-2), IrP 2-rGO shows overpotentials of 8, 51 and 13 millivolts in 0.5 M dilute sulfuric acid, 1.0 M PBS and 1.0 M potassium hydroxide solutions, respectively. Additionally, IrP 2-rGO also exhibits exceptional HOR performance in 0.1 M HClO 4 medium. Therefore, this work offers a vital addition to the developing a number of PMPs with excellent activity towards HOR and HER.

Nano-Micro Letters, 2020

Hydrogen, a renewable and outstanding energy carrier with zero carbon dioxide emission, is regard... more Hydrogen, a renewable and outstanding energy carrier with zero carbon dioxide emission, is regarded as the best alternative to fossil fuels. The most preferred route to large-scale production of hydrogen is by water electrolysis from the intermittent sources (e.g., wind, solar, hydro, and tidal energy). However, the efficiency of water electrolysis is very much dependent on the activity of electrocatalysts. Thus, designing high-effective, stable, and cheap materials for hydrogen evolution reaction (HER) could have a substantial impact on renewable energy technologies. Recently, single-atom catalysts (SACs) have emerged as a new frontier in catalysis science, because SACs have maximum atom-utilization efficiency and excellent catalytic reaction activity. Various synthesis methods and analytical techniques have been adopted to prepare and characterize these SACs. In this review, we discuss recent progress on SACs synthesis, characterization methods, and their catalytic applications. P...

Journal of The Electrochemical Society, 2019

Materials, 2019

In this work, we investigated three types of graphene (i.e., home-made G, G V4, and G V20) with d... more In this work, we investigated three types of graphene (i.e., home-made G, G V4, and G V20) with different size and morphology, as additives to a lithium iron phosphate (LFP) cathode for the lithium-ion battery. Both the LFP and the two types of graphene (G V4 and G V20) were sourced from industrial, large-volume manufacturers, enabling cathode production at low cost. The use of wrinkled and/or large pieces of a graphene matrix shows promising electrochemical performance when used as an additive to the LFP, which indicates that the features of large and curved graphene pieces enable construction of a more effective conducting network to realize the full potential of the active materials. Specifically, compared to pristine LFP, the LFP/G, LFP/G V20, and LFP/G V4 show up to a 9.2%, 6.9%, and 4.6% increase, respectively, in a capacity at 1 C. Furthermore, the LFP combined with graphene exhibits a better rate performance than tested with two different charge/discharge modes. Moreover, fr...

The Journal of Physical Chemistry C, 2017

Platinum–ruthenium (PtRu) nanoparticles (NPs) were evaporatively deposited in a 1:1 mass ratio on... more Platinum–ruthenium (PtRu) nanoparticles (NPs) were evaporatively deposited in a 1:1 mass ratio onto carbon paper, using three different orders of deposition: Pt deposited onto Ru, Ru deposited onto Pt, and both Pt and Ru deposited simultaneously. The three samples were further annealed at 650 °C for 1.5 h. A sample of Pt NPs on carbon paper was also prepared as a reference. All the deposits and the reference (a total of seven samples) were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and electrochemical techniques, in order to investigate the relationship between their catalytic surface chemical properties and their electrocatalytic activities during the methanol oxidation reaction. The simultaneous deposition of Pt and Ru demonstrated higher electrocatalytic activity, as well as excellent chronoamperometric stability, compared to either sequential deposition. This can be attributed to the synerg...

Journal of Materials Chemistry A, 2018

Litchi-like porous Fe/N/C spheres with atomically dispersed FeNx promoted by sulfur are highly ef... more Litchi-like porous Fe/N/C spheres with atomically dispersed FeNx promoted by sulfur are highly efficient electrocatalysts for high-power Zn–air batteries.

Energy & Environmental Science, 2018

Micropores are largely responsible for Fe/N/C catalytic activity, but are also intrinsically resp... more Micropores are largely responsible for Fe/N/C catalytic activity, but are also intrinsically responsible for the rapid initial performance loss in PEMFC.

$Research paper thumbnail of {"__content__"=>"Pt/TiSi -NCNT Novel Janus Nanostructure: A New Type of High-Performance Electrocatalyst.", "sub"=>{"__content__"=>"x"}}$

ACS applied materials & interfaces, Jan 4, 2018

Novel Janus nanostructured electrocatalyst (Pt/TiSi -NCNT) was prepared by first sputtering TiSi ... more Novel Janus nanostructured electrocatalyst (Pt/TiSi -NCNT) was prepared by first sputtering TiSi on one side of N-doped carbon nanotubes (NCNTs), followed by wet chemical deposition of Pt nanoparticles (NPs) on the other side. Transmission electron microscopy (TEM) studies showed that the Pt NPs are mainly deposited on the NCNT surface where no TiSi (i.e., between the gaps of TiSi film). This feature could benefit the increase in the stability of the Pt NP catalyst. Indeed, compared to the state-of-the-art commercial Pt/C catalyst, this novel Pt/TiSi -NCNT Janus structure showed ∼3 times increase in stability as well as significantly improved CO tolerance. The obvious performance enhancement could be attributed to the better corrosion resistance of TiSi and NCNTs than the carbon black that is used in the commercial Pt/C catalyst. Pt/TiSi -NCNT Janus nanostructures open the door for designing new type of high-performance electrocatalyst for fuel cells and other oxygen reduction react...

Catalysts, 2016

Graphene family materials, including graphene quantum dots (GQDs), graphene nanoribbons (GNRs) an... more Graphene family materials, including graphene quantum dots (GQDs), graphene nanoribbons (GNRs) and 3D graphene (3D-G), have attracted much research interest for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, due to their unique structural characteristics, such as abundant activate sites, edge effects and the interconnected network. In this review, we summarize recent developments in fabricating various new graphene family materials and their applications for use as ORR electrocatalysts. These new graphene family materials play an important role in improving the ORR performance, thus promoting the practical use in metal-air batteries and fuel cells.

ACS applied materials & interfaces, Jan 16, 2016

Tuna is one of the most rapid and distant swimmers. Its unique gill structure with the porous lam... more Tuna is one of the most rapid and distant swimmers. Its unique gill structure with the porous lamellae promotes fast oxygen exchange that guarantees tuna's high metabolic and athletic demands. Inspired by this specific structure, we designed and fabricated microporous graphene nanoplatelets (GNPs)-based Fe/N/C electrocatalysts for oxygen reduction reaction (ORR). Careful control of GNP structure leads to the increment of microporosity, which influences the O2 adsorption positively and desorption oppositely, resulting in enhanced O2 diffusion, while experiencing reduced ORR kinetics. Working in the cathode of proton-exchange membrane fuel cells, the GNP catalysts require a compromise between adsorption/desorption for effective O2 exchange, and as a result, appropriate microporosity is needed. In this work, the highest power density, 521 mW·cm(-2), at zero back pressure is achieved.

Catalysts, 2015

Nitrogen-doped carbon materials, including nitrogen-doped carbon nanotubes (NCNTs) and nitrogen-d... more Nitrogen-doped carbon materials, including nitrogen-doped carbon nanotubes (NCNTs) and nitrogen-doped graphene (NG), have attracted increasing attention for oxygen reduction reaction (ORR) in metal-air batteries and fuel cell applications, due to their optimal properties including excellent electronic conductivity, 4e − transfer and superb mechanical properties. Here, the recent progress of NCNTs-and NG-based catalysts for ORR is reviewed. Firstly, the general preparation routes of these two N-doped carbon-allotropes are introduced briefly, and then a special emphasis is placed on the developments of both NCNTs and NG as promising metal-free catalysts and/or catalyst support materials for ORR. All these efficient ORR electrocatalysts feature a low cost, high durability and excellent performance, and are thus the key factors in accelerating the widespread commercialization of metal-air battery and fuel cell technologies.

Journal of Nanotechnology, 2012

The current materials used in proton exchange membrane fuel cells (PEMFCs) are not sufficiently d... more The current materials used in proton exchange membrane fuel cells (PEMFCs) are not sufficiently durable for commercial deployment. One of the major challenges lies in the development of an inexpensive, efficient, and highly durable and active electrocatalyst. Here a new type of carbon-free Pt/Nb-TiO2electrocatalyst has been reported. Mesoporous Nb-TiO2hollow spheres were synthesized by the sol-gel method using polystyrene (PS) sphere templates. Pt nanoparticles (NPs) were then deposited onto mesoporous Nb-TiO2hollow spheres via a simple wet-chemical route in aqueous solution, without the need for surfactants or potentiostats. The growth densities of Pt NPs on Nb-TiO2supports could be easily modulated by simply adjusting the experimental parameters. Electrochemical studies of Pt/Nb-TiO2show much enhanced activity and stability than commercial E-TEK Pt/C catalyst. PtNP/Nb-TiO2is a promising new cathode catalyst for PEMFC applications.

Scientific Reports, 2013

Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and au... more Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle. The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the excellent performance. This work is anticipated to form the basis for the exploration of a next generation of highly efficient single-atom catalysts for various applications.

Scientific reports, 2013

Controlling the morphology of Pt nanostructures can provide opportunities to greatly increase the... more Controlling the morphology of Pt nanostructures can provide opportunities to greatly increase their activity and stability. Porous dendritic Pt nanotubes were successfully synthesized by a facile, cost-effective aqueous solution method at room temperature in large scale. These unique structures are porous, hollow, hierarchical, and single crystalline, which not only gives them a large surface area with high catalyst utilization, but also improves mass transport and gas diffusion. These novel Pt structures exhibited significantly improved catalytic activity (4.4 fold) for oxygen reduction reaction (ORR) and greatly enhanced durability (6.1 fold) over that of the state-of-the-art commercial Pt/C catalyst. This work provides a promising approach to the design of highly efficient next-generation electrocatalysts.