QINGFENG ZHAI - Academia.edu (original) (raw)

Papers by QINGFENG ZHAI

Research paper thumbnail of Design of Stretchable Holey Gold Biosensing Electrode for Real-Time Cell Monitoring

In bioelectronics, gold thin films have been widely used as sensing electrodes for probing biolog... more In bioelectronics, gold thin films have been widely used as sensing electrodes for probing biological events due to their high conductivity, chemical inertness, biocompatibility, wide electrochemical window and facile surface modification. However, they are intrinsically not stretchable, which limits their applications in detecting biological reactions when soft biological system is mechanically deformed. Here, we report on nanosphere lithography-based strategy to generate ordered microhole gold thin film electrodes supported by elastomeric substrates. Both experimental and theoretical studies show that the presence of microholes substantially suppresses the catastrophic crack propagation-the main reason for electrical failure for continuous gold film. As a result, the holey gold film achieves a ~94% stretchable limit after which conductivity is lost, in contrast to ~4% for non-structured counterpart. Furthermore, the pinhole gold electrode is successfully used to monitor H2O2 released from living cells under dynamic stretching conditions.

Research paper thumbnail of Carbon-Based Metal-Free Electrocatalysts: Past, Present and Future

Metrics & More Article Recommendations * sı Supporting Information CONSPECTUS: Due to the overuse... more Metrics & More Article Recommendations * sı Supporting Information CONSPECTUS: Due to the overuse of fossil fuels, various detrimental effects along with the excess CO 2 emissions have induced global warming and sea-level rising. To tackle climate change and provide a cleaner environment for the air we breathe and water we consume, the existing energy mix needs to be changed into fossil-free, clean, renewable energy with zero emission (e.g., fuel cells). While providing a promising and scalable strategy to the energy and environmental challenges, renewable energy processes often involve noble-metal-based catalysts (i.e., Pt, RuO 2). However, the disadvantages of noblemetal-based catalysts, including their high cost and scarcity, have hampered the large-scale application of renewable energy technologies. In 2009, we discovered earth-abundant carbon materials functioning as efficient low-cost, carbon-based metal-free electrocatalysts (C-MFECs) attractive for renewable energy and environmental remediation. Since then, C-MFECs have become an emerging new research field over the world. They are demonstrated to be efficient multifunctional catalysts for various key reactions important to renewable energy and environmental technologies, including oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO 2 reduction reaction (CO 2 RR), and N 2 reduction reaction (NRR), to name a few. Charge transfer/redistribution induced by heteroatom (e.g., N) and/or defect doping was recognized as the driving force for the metal-free catalytic activities. This finding has been used as a guidance to design and develop various new and multifunctional C-MFECs for many reactions even beyond the renewable energy and environmental remediation. In this Account, we first summarize our previous work on the development and mechanistic understanding of C-MFECs for ORR, HER, and OER to promote renewable energy conversion and storage. Then, we present recent advances in C-MFECs for new important reactions for environment remediation (e.g., CO 2 RR, NRR), seawater splitting, and metal−CO 2 batteries. However, different dopant locations for C-MFECs even with the same doping element and content can cause variable catalytic properties for heteroatom-doped carbon materials. Therefore, vast opportunities remain for further developing numerous innovative C-MFECs with defined structures to gain a better understanding of their structure-based properties. In this context, we finally conclude with the current challenges and future perspectives in this exciting field.

Research paper thumbnail of Mechanically-gated Electrochemical Ionic Channels With Chemically Modified Vertically Aligned Gold Nanowires

iScience, 2021

Mechanically-gated ion channels play an important role in the human body, whereas it is challengi... more Mechanically-gated ion channels play an important role in the human body, whereas it is challenging to design artificial mechanically-controlled ionic transport devices as the intrinsically rigidity of traditional electrodes. Here, we report on a mechanically-gated electrochemical channel by virtue of vertically aligned gold nanowires (v-AuNWs) as 3D stretchable electrodes. By surface modification with a self-assembled 1-Dodecanethiol monolayer, the v-AuNWs become hydrophobic and inaccessible to hydrated redox species (e.g., Fe ( CN ) 6 3 - / 4 - and Ru ( bpy ) 3 2 + ). Under mechanical strains, the closely-packed v-AuNWs unzip/crack to generate ionic channels to enable redox reactions, giving rise to increases in Faradaic currents. The redox current increases with the strain level until it reaches a certain threshold value, and then decreases as the strain-induced conductivity decreases. The good reversible "on-off" behaviors for multiple cycles were also demonstrated. The results presented demonstrate a new strategy to control redox reactions simply by tensile strain, indicating the potential applications in future soft smart mechanotransduction devices.

Research paper thumbnail of Skin‐Like Stretchable Fuel Cell Based on Gold‐Nanowire‐Impregnated Porous Polymer Scaffolds

Research paper thumbnail of In vitro and in vivo uterine metabolic disorders induced by silica nanoparticle through the AMPK signaling pathway

Science of The Total Environment

Research paper thumbnail of Stretchable gold fiber-based wearable textile electrochemical biosensor for lactate monitoring in sweat

Research paper thumbnail of Recent advances in flexible/stretchable batteries and integrated devices

Research paper thumbnail of Vertically Aligned Gold Nanowires as Stretchable and Wearable Epidermal Ion-Selective Electrode for Noninvasive Multiplexed Sweat Analysis

Research paper thumbnail of Stretchable gold fiber-based wearable electrochemical sensor toward pH monitoring

Journal of Materials Chemistry B

A stretchable gold fiber-based wearable electrochemical pH two-electrodes sensing system for huma... more A stretchable gold fiber-based wearable electrochemical pH two-electrodes sensing system for human health monitoring.

Research paper thumbnail of Intrinsically Stretchable Fuel Cell Based on Enokitake‐Like Standing Gold Nanowires

Advanced Energy Materials

Research paper thumbnail of Real-Time and In-Situ Monitoring of H2O2 Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires

Research paper thumbnail of Local Crack‐Programmed Gold Nanowire Electronic Skin Tattoos for In‐Plane Multisensor Integration

Research paper thumbnail of Soft and Stretchable Electrochemical Biosensors

Research paper thumbnail of Highly Stretchable and Strain-Insensitive Fiber-Based Wearable Electrochemical Biosensor to Monitor Glucose in the Sweat

Research paper thumbnail of Paper-based electrochemiluminescence bipolar conductivity sensing mechanism: A critical supplement for the bipolar system

Journal of Electroanalytical Chemistry

Research paper thumbnail of Embedding Pinhole Vertical Gold Nanowire Electronic Skins for Braille Recognition

Research paper thumbnail of Enokitake Mushroom-like Standing Gold Nanowires toward Wearable Noninvasive Bimodal Glucose and Strain Sensing

ACS Applied Materials & Interfaces

Research paper thumbnail of Gold-silver bimetallic nanoclusters with enhanced fluorescence for highly selective and sensitive detection of glutathione

Sensors and Actuators B: Chemical

Research paper thumbnail of Vertical Gold Nanowires Stretchable Electrochemical Electrodes

Research paper thumbnail of Point-of-Care Diagnoses: Flexible Patterning Technique for Self-Powered Wearable Sensors

Analytical chemistry, Jan 16, 2018

This paper demonstrated the fabrication of a facile, low-cost, and self-powered platform for poin... more This paper demonstrated the fabrication of a facile, low-cost, and self-powered platform for point-of-care fitness level and athletic performance monitoring sensor using electrochemical lithography method and its application in body fluid sensing. Flexible Au/prussian blue electrode was employed as the indicating electrode, where the color change was an indication of fitness level and athletic performance. A piece of Al foil, Au/multiwalled carbon nanotubes (MWCNTs)-glucose dehydrogenase, and Au/polymethylene blue-MWCNTs-lactic dehydrogenase electrodes were used for the detection of ionic strength, glucose, and lactic acid in sweat, respectively, which allows the sensor to work without any extra instrumentation and the output signal can be recognized by the naked eyes. The advantages of these sensors are (1) self-powered; (2) readily applicable to the detection of any electroactive substance by an electrochromic material; (3) easy to fabricate via two steps of EDP; and (4) point-of-...

Research paper thumbnail of Design of Stretchable Holey Gold Biosensing Electrode for Real-Time Cell Monitoring

In bioelectronics, gold thin films have been widely used as sensing electrodes for probing biolog... more In bioelectronics, gold thin films have been widely used as sensing electrodes for probing biological events due to their high conductivity, chemical inertness, biocompatibility, wide electrochemical window and facile surface modification. However, they are intrinsically not stretchable, which limits their applications in detecting biological reactions when soft biological system is mechanically deformed. Here, we report on nanosphere lithography-based strategy to generate ordered microhole gold thin film electrodes supported by elastomeric substrates. Both experimental and theoretical studies show that the presence of microholes substantially suppresses the catastrophic crack propagation-the main reason for electrical failure for continuous gold film. As a result, the holey gold film achieves a ~94% stretchable limit after which conductivity is lost, in contrast to ~4% for non-structured counterpart. Furthermore, the pinhole gold electrode is successfully used to monitor H2O2 released from living cells under dynamic stretching conditions.

Research paper thumbnail of Carbon-Based Metal-Free Electrocatalysts: Past, Present and Future

Metrics & More Article Recommendations * sı Supporting Information CONSPECTUS: Due to the overuse... more Metrics & More Article Recommendations * sı Supporting Information CONSPECTUS: Due to the overuse of fossil fuels, various detrimental effects along with the excess CO 2 emissions have induced global warming and sea-level rising. To tackle climate change and provide a cleaner environment for the air we breathe and water we consume, the existing energy mix needs to be changed into fossil-free, clean, renewable energy with zero emission (e.g., fuel cells). While providing a promising and scalable strategy to the energy and environmental challenges, renewable energy processes often involve noble-metal-based catalysts (i.e., Pt, RuO 2). However, the disadvantages of noblemetal-based catalysts, including their high cost and scarcity, have hampered the large-scale application of renewable energy technologies. In 2009, we discovered earth-abundant carbon materials functioning as efficient low-cost, carbon-based metal-free electrocatalysts (C-MFECs) attractive for renewable energy and environmental remediation. Since then, C-MFECs have become an emerging new research field over the world. They are demonstrated to be efficient multifunctional catalysts for various key reactions important to renewable energy and environmental technologies, including oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO 2 reduction reaction (CO 2 RR), and N 2 reduction reaction (NRR), to name a few. Charge transfer/redistribution induced by heteroatom (e.g., N) and/or defect doping was recognized as the driving force for the metal-free catalytic activities. This finding has been used as a guidance to design and develop various new and multifunctional C-MFECs for many reactions even beyond the renewable energy and environmental remediation. In this Account, we first summarize our previous work on the development and mechanistic understanding of C-MFECs for ORR, HER, and OER to promote renewable energy conversion and storage. Then, we present recent advances in C-MFECs for new important reactions for environment remediation (e.g., CO 2 RR, NRR), seawater splitting, and metal−CO 2 batteries. However, different dopant locations for C-MFECs even with the same doping element and content can cause variable catalytic properties for heteroatom-doped carbon materials. Therefore, vast opportunities remain for further developing numerous innovative C-MFECs with defined structures to gain a better understanding of their structure-based properties. In this context, we finally conclude with the current challenges and future perspectives in this exciting field.

Research paper thumbnail of Mechanically-gated Electrochemical Ionic Channels With Chemically Modified Vertically Aligned Gold Nanowires

iScience, 2021

Mechanically-gated ion channels play an important role in the human body, whereas it is challengi... more Mechanically-gated ion channels play an important role in the human body, whereas it is challenging to design artificial mechanically-controlled ionic transport devices as the intrinsically rigidity of traditional electrodes. Here, we report on a mechanically-gated electrochemical channel by virtue of vertically aligned gold nanowires (v-AuNWs) as 3D stretchable electrodes. By surface modification with a self-assembled 1-Dodecanethiol monolayer, the v-AuNWs become hydrophobic and inaccessible to hydrated redox species (e.g., Fe ( CN ) 6 3 - / 4 - and Ru ( bpy ) 3 2 + ). Under mechanical strains, the closely-packed v-AuNWs unzip/crack to generate ionic channels to enable redox reactions, giving rise to increases in Faradaic currents. The redox current increases with the strain level until it reaches a certain threshold value, and then decreases as the strain-induced conductivity decreases. The good reversible "on-off" behaviors for multiple cycles were also demonstrated. The results presented demonstrate a new strategy to control redox reactions simply by tensile strain, indicating the potential applications in future soft smart mechanotransduction devices.

Research paper thumbnail of Skin‐Like Stretchable Fuel Cell Based on Gold‐Nanowire‐Impregnated Porous Polymer Scaffolds

Research paper thumbnail of In vitro and in vivo uterine metabolic disorders induced by silica nanoparticle through the AMPK signaling pathway

Science of The Total Environment

Research paper thumbnail of Stretchable gold fiber-based wearable textile electrochemical biosensor for lactate monitoring in sweat

Research paper thumbnail of Recent advances in flexible/stretchable batteries and integrated devices

Research paper thumbnail of Vertically Aligned Gold Nanowires as Stretchable and Wearable Epidermal Ion-Selective Electrode for Noninvasive Multiplexed Sweat Analysis

Research paper thumbnail of Stretchable gold fiber-based wearable electrochemical sensor toward pH monitoring

Journal of Materials Chemistry B

A stretchable gold fiber-based wearable electrochemical pH two-electrodes sensing system for huma... more A stretchable gold fiber-based wearable electrochemical pH two-electrodes sensing system for human health monitoring.

Research paper thumbnail of Intrinsically Stretchable Fuel Cell Based on Enokitake‐Like Standing Gold Nanowires

Advanced Energy Materials

Research paper thumbnail of Real-Time and In-Situ Monitoring of H2O2 Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires

Research paper thumbnail of Local Crack‐Programmed Gold Nanowire Electronic Skin Tattoos for In‐Plane Multisensor Integration

Research paper thumbnail of Soft and Stretchable Electrochemical Biosensors

Research paper thumbnail of Highly Stretchable and Strain-Insensitive Fiber-Based Wearable Electrochemical Biosensor to Monitor Glucose in the Sweat

Research paper thumbnail of Paper-based electrochemiluminescence bipolar conductivity sensing mechanism: A critical supplement for the bipolar system

Journal of Electroanalytical Chemistry

Research paper thumbnail of Embedding Pinhole Vertical Gold Nanowire Electronic Skins for Braille Recognition

Research paper thumbnail of Enokitake Mushroom-like Standing Gold Nanowires toward Wearable Noninvasive Bimodal Glucose and Strain Sensing

ACS Applied Materials & Interfaces

Research paper thumbnail of Gold-silver bimetallic nanoclusters with enhanced fluorescence for highly selective and sensitive detection of glutathione

Sensors and Actuators B: Chemical

Research paper thumbnail of Vertical Gold Nanowires Stretchable Electrochemical Electrodes

Research paper thumbnail of Point-of-Care Diagnoses: Flexible Patterning Technique for Self-Powered Wearable Sensors

Analytical chemistry, Jan 16, 2018

This paper demonstrated the fabrication of a facile, low-cost, and self-powered platform for poin... more This paper demonstrated the fabrication of a facile, low-cost, and self-powered platform for point-of-care fitness level and athletic performance monitoring sensor using electrochemical lithography method and its application in body fluid sensing. Flexible Au/prussian blue electrode was employed as the indicating electrode, where the color change was an indication of fitness level and athletic performance. A piece of Al foil, Au/multiwalled carbon nanotubes (MWCNTs)-glucose dehydrogenase, and Au/polymethylene blue-MWCNTs-lactic dehydrogenase electrodes were used for the detection of ionic strength, glucose, and lactic acid in sweat, respectively, which allows the sensor to work without any extra instrumentation and the output signal can be recognized by the naked eyes. The advantages of these sensors are (1) self-powered; (2) readily applicable to the detection of any electroactive substance by an electrochromic material; (3) easy to fabricate via two steps of EDP; and (4) point-of-...