Covalent functionalization of AlN nanotubes with acetylene

► Functionalization of AlN nanotube (AlNNT) with acetylene investigated by DFT. ► Acetylene preferably tends to [2+2] addition on Al-N bonds of the tube surface. ► HOMO-LUMO gap of AlNNT has not changed significantly upon the functionalization. ► Global hardness and electrophilicity of AlNNT are slightly decreased. ► Field electron emission from the AlNNT surface may be improved upon this process.