Browsing by Author "Zhang, Xiao"

Now showing 1 - 4 of 4
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    CO2/carbonate-mediated electrochemical water oxidation to hydrogen peroxide
    (Springer Nature, 2022) Fan, Lei; Bai, Xiaowan; Xia, Chuan; Zhang, Xiao; Zhao, Xunhua; Xia, Yang; Wu, Zhen-Yu; Lu, Yingying; Liu, Yuanyue; Wang, Haotian
    Electrochemical water oxidation reaction (WOR) to hydrogen peroxide (H2O2) via a 2e− pathway provides a sustainable H2O2 synthetic route, but is challenged by the traditional 4e− counterpart of oxygen evolution. Here we report a CO2/carbonate mediation approach to steering the WOR pathway from 4e− to 2e−. Using fluorine-doped tin oxide electrode in carbonate solutions, we achieved high H2O2 selectivity of up to 87%, and delivered unprecedented H2O2 partial currents of up to 1.3 A cm−2, which represents orders of magnitude improvement compared to literature. Molecular dynamics simulations, coupled with electron paramagnetic resonance and isotope labeling experiments, suggested that carbonate mediates the WOR pathway to H2O2 through the formation of carbonate radical and percarbonate intermediates. The high selectivity, industrial-relevant activity, and good durability open up practical opportunities for delocalized H2O2 production.
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    Hydrogen Peroxide Electrosynthesis in a Strong Acidic Environment Using Cationic Surfactants
    (American Chemical Society, 2024) Adler, Zachary; Zhang, Xiao; Feng, Guangxia; Shi, Yaping; Zhu, Peng; Xia, Yang; Shan, Xiaonan; Wang, Haotian
    The two-electron oxygen reduction reaction (2e–-ORR) can be exploited for green production of hydrogen peroxide (H2O2), but it still suffers from low selectivity in an acidic electrolyte when using non-noble metal catalysts. Here, inspired by biology, we demonstrate a strategy that exploits the micellization of surfactant molecules to promote the H2O2 selectivity of a low-cost carbon black catalyst in strong acid electrolytes. The surfactants near the electrode surface increase the oxygen solubility and transportation, and they provide a shielding effect that displaces protons from the electric double layer (EDL). Compared with the case of a pure acidic electrolyte, we find that, when a small number of surfactant molecules were added to the acid, the H2O2 Faradaic efficiency (FE) was improved from 12% to 95% H2O2 under 200 mA cm–2, suggesting an 8-fold improvement. Our in situ surface enhanced Raman spectroscopy (SERS) and optical microscopy (OM) studies suggest that, while the added surfactant reduces the electrode’s hydrophobicity, its micelle formation could promote the O2 gas transport and its hydrophobic tail could displace local protons under applied negative potentials during catalysis, which are responsible for the improved H2O2 selectivity in strong acids.
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    Super-stretchable, Transparent Carbon Nanotube-Based Capacitive Strain Sensors for Human Motion Detection
    (Nature Publishing Group, 2013) Cai, Le; Song, Li; Luan, Pingshan; Zhang, Qiang; Zhang, Nan; Gao, Qingqing; Zhao, Duan; Zhang, Xiao; Tu, Min; Yang, Feng; Zhou, Wenbin; Fan, Qingxia; Luo, Jun; Zhou, Weiya; Ajayan, Pulickel M.; Xie, Sishen
    Realization of advanced bio-interactive electronic devices requires mechanically compliant sensors with the ability to detect extremely large strain. Here, we design a new multifunctional carbon nanotube (CNT) based capacitive strain sensors which can detect strains up to 300% with excellent durability even after thousands of cycles. The CNT-based strain gauge devices exhibit deterministic and linear capacitive response throughout the whole strain range with a gauge factor very close to the predicted value (strictly 1), representing the highest sensitivity value. The strain tests reveal the presented strain gauge with excellent dynamic sensing ability without overshoot or relaxation, and ultrafast response at sub-second scale. Coupling these superior sensing capabilities to the high transparency, physical robustness and flexibility, we believe the designed stretchable multifunctional CNT-based strain gauge may have various potential applications in human friendly and wearable smart electronics, subsequently demonstrated by our prototypical data glove and respiration monitor.
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    Three-chamber electrochemical reactor for selective lithium extraction from brine
    (National Academy of Sciences, 2024) Feng, Yuge; Park, Yoon; Hao, Shaoyun; Fang, Zhiwei; Terlier, Tanguy; Zhang, Xiao; Qiu, Chang; Zhang, Shoukun; Chen, Fengyang; Zhu, Peng; Nguyen, Quan; Wang, Haotian; Biswal, Sibani Lisa; Rice Advanced Material Institute
    Efficient lithium recovery from geothermal brines is crucial for the battery industry. Current electrochemical separation methods struggle with the simultaneous presence of Na+, K+, Mg2+, and Ca2+ because these cations are similar to Li+, making it challenging to separate effectively. We address these challenges with a three-chamber reactor featuring a polymer porous solid electrolyte in the middle layer. This design improves the transference number of Li+ (tLi+) by 2.1 times compared to the two-chamber reactor and also reduces the chlorine evolution reaction, a common side reaction in electrochemical lithium extraction, to only 6.4% in Faradaic Efficiency. Employing a lithium-ion conductive glass ceramic (LICGC) membrane, the reactor achieved high tLi+ of 97.5% in LiOH production from simulated brine, while the concentrations of Na+ K+, Mg2+, and Ca2+ are below the detection limit. Electrochemical experiments and surface analysis elucidated the cation transport mechanism, highlighting the impact of Na+ on Li+ migration at the LICGC interface.