In Situ Surface Restraint-Induced Synthesis of Transition-Metal Nitride Ultrathin Nanocrystals as Ultrasensitive SERS Substrate with Ultrahigh Durability

It is a major challenge to synthesize crystalline transition-metal nitride (TMN) ultrathin nanocrystals due to their harsh reaction conditions. Herein, we report that highly crystalline tungsten nitride (W2N, WN, W3N4, W2N3) nanocrystals with small size and excellent dispersibility are prepared by a mild and general in situ surface restraint-induced growth method. These ultrafine tungsten nitride nano crystals are immobilized in ultrathin carbon layers, forming an interesting hybrid nanobelt structure. The hybrid WN/C nanobelts exhibit a strong localized surface plasmon resonance (LSPR) effect and surface-enhanced Raman scattering (SERS) effect, including a lowest detection limit of 1 x 10(-12) M and a Raman enhancement factor of 6.5 x 10(8) comparable to noble metals, which may be one of the best records for non-noble metal SERS substrates. Moreover, they even can maintain the SERS performance in a variety of harsh environments, showing outstanding corrosion resistance, radiation resistance, and oxidation resistance, which is not available on traditional noble metal and semiconductor SERS substrates. A synergistic Raman enhancement mechanism of LSPR and interface charge transfer is found in the carbon coated tungsten nitride substrate. A microfluidic SERS channel integrating the enrichment and detection of trace substances is constructed with the WN/C nanobelt, which realizes high-throughput dynamic SERS analysis.

Automated summary

This study presents a mild and general in situ surface restraint-induced growth method for the preparation of highly crystalline tungsten nitride nanocrystals with excellent dispersibility, forming a hybrid structure in ultrathin carbon layers. These hybrid nanobelts exhibit strong localized surface plasmon resonance and surface-enhanced Raman scattering effects, with outstanding corrosion resistance, radiation resistance, and oxidation resistance, maintaining SERS performance in harsh environments. The synergistic Raman enhancement mechanism of LSPR and interface charge transfer is found in the carbon coated tungsten nitride substrate, enabling high-throughput dynamic SERS analysis in a microfluidic SERS channel.