Covalent Functionalization of Violet Phosphorus Nanosheets for Room-Temperature NO2 Sensing

Violet phosphorus possesses unique band structure, making it a promising candidate for electronic device applications. This study presents covalently functionalized violet phosphorus nanosheets (VPNSs) for sensitive and selective detection of nitrogen dioxide (NO2) gases at room temperature. The modified VPNSs were facilely synthesized via liquid-phase exfoliation and subsequent covalent functionalization with nitrophenyl groups (VPNSs-PhNO2), significantly changing the intrinsic electronic properties and improving their gas-sensing performance. SEM and FTIR analyses confirmed the effective attachment of nitrophenyl groups which contributed to their enhanced sensitivity and selectivity response towards NO2 gases. The sensing results revealed that as-modified VPNSs exhibited markedly faster response and recovery times compared to conventional sensors. It is suggested that the nitro groups not only facilitated the semiconductor type transition but also improved the interaction of VPNSs with NO2 gas. These innovative designs of VPNSs-PhNO2 sensors offer a solution for highly sensitive NO2 detection.