Nanosecond laser shock detonation of nanodiamonds:from laser-matter interaction to graphite-to-diamond phase transition

Nanodiamonds(NDs)have been widely explored for applications in drug delivery,optical bioimaging,sensors,quantum computing,and others.Room-temperature nanomanufacturing of NDs in open air using confined laser shock detonation(CLSD)emerges as a novel manufacturing strategy for ND fabrication.However,the fundamental process mechanism remains unclear.This work investigates the underlying mechanisms responsible for nanomanufacturing of NDs during CLSD with a focus on the laser-matter interaction,the role of the confining effect,and the graphite-to-diamond transition.Specifically,a first-principles model is integrated with a molecular dynamics simulation to describe the laser-induced thermo-hydrodynamic phenomena and the graphite-to-diamond phase transition during CLSD.The simulation results elucidate the confining effect in determining the material’s responses to laser irradiation in terms of the temporal and spatial evolutions of temperature,pressure,electron number density,and particle velocity.The integrated model demonstrates the capability of predicting the laser energy threshold for ND synthesis and the efficiency of ND nucleation under varying processing parameters.This research will provide significant insights into CLSD and advance this nanomanufacturing strategy for the fabrication of NDs and other high-temperature-high-pressure synthesized nanomaterials towards extensive applications.

Platinum nanoparticles supported MoS2 nanosheet for simultaneous detection of dopamine and uric acid

Herein, platinum nanoparticles-decorated molybdenum disulfide （PtNPs@MoS2） nanocomposite has been synthesized via a microwave-assisted hydrothermal method, which was characterized by transmission electron microscopy （TEM） and powder X-ray diffraction （XRD）. This MoSz-based nanocomposite modified glass carbon electrode （PtNPs@MoSz/GCE） exhibited excellent electrocatalytic activity toward dopamine （DA） and uric acid （UA） due to their synergistic effect. Two well-defined oxidation peaks of DA and UA were obtained at PtNPs@MoS2/GCE with a large peak separation of 160 mV （DA-UA）, sug- gesting that the modified electrode could individually or simultaneously analyze DA and AA. Under the optimal conditions, the peak currents of DA and UA were linearly dependent on their concentrations in the range of 0.5-150 and 5-1000 gmol/L with detection limit of 0.17 and 0.98 gmol/L, respectively. The proposed MoSz-based sensor can also be employed to examine DA and UA in real samples with satisfactory results. Therefore, the PtNPs@MoS2 nanocomposite might offer a good possibil- ity for electrochemical sensing and other electrocatalytic applications.