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Xiao Zhang

Bio: Xiao Zhang is an academic researcher from Stanford University. The author has contributed to research in topics: Carbon nanotube & Catalysis. The author has an hindex of 17, co-authored 36 publications receiving 1341 citations. Previous affiliations of Xiao Zhang include Southern University of Science and Technology & Zhejiang University.

Papers
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Journal ArticleDOI
Xiao Zhang1, Xueqian Li1, Du Zhang1, Neil Qiang Su1, Weitao Yang1, Henry O. Everitt1, Jie Liu1 
TL;DR: This work shows how the recently demonstrated plasmonic behaviour of rhodium nanoparticles profoundly improves their already excellent catalytic properties by simultaneously reducing the activation energy and selectively producing a desired but kinetically unfavourable product for the important carbon dioxide hydrogenation reaction.
Abstract: Photocatalysis has not found widespread industrial adoption, in spite of decades of active research, because the challenges associated with catalyst illumination and turnover outweigh the touted advantages of replacing heat with light. A demonstration that light can control product selectivity in complex chemical reactions could prove to be transformative. Here, we show how the recently demonstrated plasmonic behaviour of rhodium nanoparticles profoundly improves their already excellent catalytic properties by simultaneously reducing the activation energy and selectively producing a desired but kinetically unfavourable product for the important carbon dioxide hydrogenation reaction. Methane is almost exclusively produced when rhodium nanoparticles are mildly illuminated as hot electrons are injected into the anti-bonding orbital of a critical intermediate, while carbon monoxide and methane are equally produced without illumination. The reduced activation energy and super-linear dependence on light intensity cause the unheated photocatalytic methane production rate to exceed the thermocatalytic rate at 350 °C. Atmospheric CO2 can be transformed into valuable hydrocarbons by reaction with H2, but CO is the favoured kinetic product. Here, Liu and co-workers show that plasmonic rhodium nanoparticles not only reduce the activation energy for CO2hydrogenation, but also photo-selectively produce methane.

341 citations

Journal ArticleDOI
TL;DR: Zhang et al. as discussed by the authors designed a series of nickel phthalocyanine molecules supported on carbon nanotubes as molecularly dispersed electrocatalysts (MDEs), achieving CO2 reduction performances that are superior to aggregated molecular catalysts in terms of stability, activity and selectivity.
Abstract: Electrochemical reduction of CO2 is a promising route for sustainable production of fuels. A grand challenge is developing low-cost and efficient electrocatalysts that can enable rapid conversion with high product selectivity. Here we design a series of nickel phthalocyanine molecules supported on carbon nanotubes as molecularly dispersed electrocatalysts (MDEs), achieving CO2 reduction performances that are superior to aggregated molecular catalysts in terms of stability, activity and selectivity. The optimized MDE with methoxy group functionalization solves the stability issue of the original nickel phthalocyanine catalyst and catalyses the conversion of CO2 to CO with >99.5% selectivity at high current densities of up to −300 mA cm−2 in a gas diffusion electrode device with stable operation at −150 mA cm−2 for 40 h. The well-defined active sites of MDEs also facilitate the in-depth mechanistic understandings from in situ/operando X-ray absorption spectroscopy and theoretical calculations on structural factors that affect electrocatalytic performance. Widespread deployment of electrochemical CO2 reduction requires low-cost catalysts that perform well at high current densities. Zhang et al. show that methoxy-functionalized nickel phthalocyanine molecules on carbon nanotubes can operate as high-performing molecularly dispersed electrocatalysts at current densities of up to −300 mA cm–2.

287 citations

Journal ArticleDOI
TL;DR: The residual nonthermal rate of the plasmon-enhanced reaction is found to grow with a superlinear dependence on illumination intensity, and its apparent quantum efficiency reaches ∼46% on a Rh/TiO2 catalyst at a surface temperature of 350 °C.
Abstract: In plasmon-enhanced heterogeneous catalysis, illumination accelerates reaction rates by generating hot carriers and hot surfaces in the constituent nanostructured metals In order to understand how photogenerated carriers enhance the nonthermal reaction rate, the effects of photothermal heating and thermal gradients in the catalyst bed must be confidently and quantitatively characterized This is a challenging task considering the conflating effects of light absorption, heat transport, and reaction energetics Here, we introduce a methodology to distinguish the thermal and nonthermal contributions from plasmon-enhanced catalysts, demonstrated by illuminated rhodium nanoparticles on oxide supports to catalyze the CO2 methanation reaction By simultaneously measuring the total reaction rate and the temperature gradient of the catalyst bed, the effective thermal reaction rate may be extracted The residual nonthermal rate of the plasmon-enhanced reaction is found to grow with a superlinear dependence on illu

228 citations

Journal ArticleDOI
Yanwen Ma1, Pan Li1, Jennifer W. Sedloff1, Xiao Zhang1, Hongbo Zhang1, Jie Liu1 
29 Jan 2015-ACS Nano
TL;DR: The performance of WSSs was revealed to decrease with increasing length due to increased resistance, revealing a key issue for graphene-based electrodes in WSSing, which could be effectively decreased by the addition of highly conductive carbon nanotubes.
Abstract: Graphene fibers are a promising electrode material for wire-shaped supercapacitors (WSSs) that can be woven into textiles for future wearable electronics. However, the main concern is their high linear resistance, which could be effectively decreased by the addition of highly conductive carbon nanotubes (CNTs). During the incorporation process, CNTs are typically preoxidized by acids or dispersed by surfactants, which deteriorates their electrical and mechanical properties. Herein, unfunctionalized few-walled carbon nanotubes (FWNTs) were directly dispersed in graphene oxide (GO) without preoxidation or surfactants, allowing them to maintain their high conductivity and perfect structure, and then used to prepare CNT-reduced GO (RGO) composite fibers by wet-spinning followed by reduction. The pristine FWNTs increased the stress strength of the parent RGO fibers from 193.3 to 385.7 MPa and conductivity from 53.3 to 210.7 S cm–1. The wire-shaped supercapacitors (WSSs) assembled based on these CNT-RGO fibers ...

187 citations

Journal ArticleDOI
TL;DR: An NIR-II fluorophore based on DSPE-mPEG encapsulated rare earth doped nanoparticles (RENPs@D SPE- mPEG), which shows inherent affinity to bone without linking any targeting ligands, and thus, it provides an alternative noninvasive and nonradiation strategy for skeletal system mapping and bone disease diagnoses.
Abstract: As a newly noninvasive emerging modality, NIR-II fluorescence imaging (1000-1700 nm) has many advantages over conventional visible and NIR-I imaging (700-900 nm). Unfortunately, only a few NIR-II fluorophores are suitable for bone imaging. Here, we report an NIR-II fluorophore based on DSPE-mPEG encapsulated rare earth doped nanoparticles (RENPs@DSPE-mPEG), which shows inherent affinity to bone without linking any targeting ligands, and thus, it provides an alternative noninvasive and nonradiation strategy for skeletal system mapping and bone disease diagnoses. Interestingly, within the NIR-II window, imaging at a longer wavelength (1345 nm) provides a higher resolution and signal-to-noise ratio than imaging at 1064 nm, even though the quantum yield at 1064 nm is 2-fold higher than that at 1345 nm. Besides bone imaging, RENPs@DSPE-mPEG show an imaging application in blood vessels and lymph nodes. Importantly, RENPs@DSPE-mPEG can be internalized by circulating white blood cells. This finding may open a window to increase efficient nanoparticle delivery in the fields such as immunotherapy and improve the diagnostic and therapeutic efficacy of cancer-targeted nanoparticles in clinical applications.

120 citations


Cited by
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Journal ArticleDOI
05 Oct 2018-Science
TL;DR: The concept of a light-dependent activation barrier is introduced to account for the effect of light illumination on electronic and thermal excitations in a single unified picture and provides insight into the specific role of hot carriers in plasmon-mediated photochemistry, which is critically important for designing energy-efficient plAsmonic photocatalysts.
Abstract: Photocatalysis based on optically active, “plasmonic” metal nanoparticles has emerged as a promising approach to facilitate light-driven chemical conversions under far milder conditions than thermal catalysis. However, an understanding of the relation between thermal and electronic excitations has been lacking. We report the substantial light-induced reduction of the thermal activation barrier for ammonia decomposition on a plasmonic photocatalyst. We introduce the concept of a light-dependent activation barrier to account for the effect of light illumination on electronic and thermal excitations in a single unified picture. This framework provides insight into the specific role of hot carriers in plasmon-mediated photochemistry, which is critically important for designing energy-efficient plasmonic photocatalysts.

668 citations

Journal ArticleDOI
TL;DR: A hollow graphene/conducting polymer composite fiber is created with high mechanical and electronic properties and used to fabricate novel fiber-shaped supercapacitors that display high energy densities and long life stability.
Abstract: A hollow graphene/conducting polymer composite fiber is created with high mechanical and electronic properties and used to fabricate novel fiber-shaped supercapacitors that display high energy densities and long life stability. The fiber supercapacitors can be woven into flexible powering textiles that are particularly promising for portable and wearable electronic devices.

620 citations

Journal ArticleDOI
TL;DR: In this paper, a rice crust-like structure was achieved through the uniform distribution of TiO2 nanoparticles on MXene Ti3C2 through calcination method and a unique rice crustlike structure of the prepared samples rendered the composite with large population of the surface active sites.

557 citations

Journal ArticleDOI
01 Sep 2018
TL;DR: A review of plasmonic catalysis can be found in this article, focusing on the underlying physical mechanisms and their application in catalysis, as well as limitations and future perspectives.
Abstract: The demonstrations of visible-light-driven chemical transformations on plasmonic metal nanostructures have led to the emergence of a new field in heterogeneous catalysis known as plasmonic catalysis The excitement surrounding plasmonic catalysis stems from the ability to use the excitation of energetic charge carriers (as opposed to heat) to drive surface chemistry This offers the opportunity to potentially discover new, more selective reaction pathways that cannot be accessed in temperature-driven catalysis In this Review, we provide a fundamental overview of plasmonic catalysis with emphasis on recent advancements in the field It is our objective to stress the importance of the underlying physical mechanisms at play in plasmonic catalysis and discuss possibilities and limitations in the field guided by these physical insights Plasmonic catalysis has recently revolutionized the field of catalysis, promising to achieve improved control over catalytic reactions by targeting specific electronic excitations In this Review, Linic and co-workers discuss the recent advances in the field, focusing on the underlying physical mechanisms and their application in catalysis, as well as limitations and future perspectives

526 citations

Journal ArticleDOI
TL;DR: This work critically summarized and comprehensively reviewed the characteristics and performance of both liquid and solid CO2 adsorbents with possible schemes for the improvement of their CO2 capture ability and advances in CO2 utilization.
Abstract: Dramatically increased CO2 concentration from several point sources is perceived to cause severe greenhouse effect towards the serious ongoing global warming with associated climate destabilization, inducing undesirable natural calamities, melting of glaciers, and extreme weather patterns. CO2 capture and utilization (CCU) has received tremendous attention due to its significant role in intensifying global warming. Considering the lack of a timely review on the state-of-the-art progress of promising CCU techniques, developing an appropriate and prompt summary of such advanced techniques with a comprehensive understanding is necessary. Thus, it is imperative to provide a timely review, given the fast growth of sophisticated CO2 capture and utilization materials and their implementation. In this work, we critically summarized and comprehensively reviewed the characteristics and performance of both liquid and solid CO2 adsorbents with possible schemes for the improvement of their CO2 capture ability and advances in CO2 utilization. Their industrial applications in pre- and post-combustion CO2 capture as well as utilization were systematically discussed and compared. With our great effort, this review would be of significant importance for academic researchers for obtaining an overall understanding of the current developments and future trends of CCU. This work is bound to benefit researchers in fields relating to CCU and facilitate the progress of significant breakthroughs in both fundamental research and commercial applications to deliver perspective views for future scientific and industrial advances in CCU.

453 citations