Browsing by Author "Meng, Andrew C."

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    Laser-induced high-entropy alloys as long-duration bifunctional electrocatalysts for seawater splitting
    (Royal Society of Chemistry, 2024) Xie, Yunchao; Xu, Shichen; Meng, Andrew C.; Zheng, Bujingda; Chen, Zhenru; Tour, James M.; Lin, Jian; NanoCarbon Center;Rice Advanced Materials Institute
    Electrocatalytic seawater splitting has garnered significant attention as a promising approach for eco-friendly, large-scale green hydrogen production. Development of high-efficiency and cost-effective electrocatalysts remains a frontier in this field. Herein, we report a rapid in situ synthesis of FeNiCoCrRu high-entropy alloy nanoparticles (HEA NPs) by direct CO2 laser induction of metal precursors on carbon paper under ambient conditions. Due to the induced ultrahigh temperature and ultrafast heating/quenching rates, FeNiCoCrRu HEA NPs with sizes ranging from 5 to 40 nm possess uniform phase homogeneity. FeNiCoCrRu HEA NPs exhibit exceptional bifunctional electrocatalytic activities, delivering overpotentials of 0.148 V at 600 mA cm−2 for the hydrogen evolution reaction and 0.353 V at 300 mA cm−2 for the oxygen evolution reaction in alkaline seawater. When assembled FeNiCoCrRu HEA NPs to an electrolyzer, it shows a negligible voltage increase at 250 mA cm−2 even after over 3000-hour operation. This superior performance can be attributed to the high-entropy design, large electrochemical specific area, and excellent chemical and structural stability. An operando Raman spectroscopy study discloses that the Ni and Ru sites serve as active sites for hydrogen evolution, while the Ni site acts as an active site for oxygen evolution. This work demonstrates a laser-induced eco-friendly nanomaterial synthesis. The systematic studies offer an in-depth understanding of HEA design and its correlation with high-efficiency seawater splitting.
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    Programmed multimaterial assembly by synergized 3D printing and freeform laser induction
    (Springer Nature, 2024) Zheng, Bujingda; Xie, Yunchao; Xu, Shichen; Meng, Andrew C.; Wang, Shaoyun; Wu, Yuchao; Yang, Shuhong; Wan, Caixia; Huang, Guoliang; Tour, James M.; Lin, Jian; Smalley-Curl Institute
    In nature, structural and functional materials often form programmed three-dimensional (3D) assembly to perform daily functions, inspiring researchers to engineer multifunctional 3D structures. Despite much progress, a general method to fabricate and assemble a broad range of materials into functional 3D objects remains limited. Herein, to bridge the gap, we demonstrate a freeform multimaterial assembly process (FMAP) by integrating 3D printing (fused filament fabrication (FFF), direct ink writing (DIW)) with freeform laser induction (FLI). 3D printing performs the 3D structural material assembly, while FLI fabricates the functional materials in predesigned 3D space by synergistic, programmed control. This paper showcases the versatility of FMAP in spatially fabricating various types of functional materials (metals, semiconductors) within 3D structures for applications in crossbar circuits for LED display, a strain sensor for multifunctional springs and haptic manipulators, a UV sensor, a 3D electromagnet as a magnetic encoder, capacitive sensors for human machine interface, and an integrated microfluidic reactor with a built-in Joule heater for nanomaterial synthesis. This success underscores the potential of FMAP to redefine 3D printing and FLI for programmed multimaterial assembly.