Hydrogen cyanide catalytic hydrolysis mechanism by Al-doped graphene: A density functional theory study

The hydrogen cyanide (HCN) hydrolysis reaction mechanism over Al-doped graphene was investigated through the density functional theory method. HCN preferentially adsorbed vertically on the Al top site to form a stable adsorption configuration. H₂O preferentially adsorbed parallel on the Al top site to form a stable adsorption configuration. The competitive adsorption of HCN and H₂O weakened the adsorption stability of each molecule over Al-doped graphene. The break of C-N and H-O bonds was the key process in the preferential fracture pathway of the C-H bond. The break of C-N and C-H bonds was the key process in the preferential fracture pathway of the H-O bond. HCN played the role of bridge in the joint adsorption process. H atom transfer and C-N bond cleavage promoted the generation of CO and NH₃. The change in the order of H atom transfer determined the reaction energy barrier. NH₂CHO was more likely to act as an intermediate to promote the hydrolysis process.

The calculation work was achieved from the Dmol³ program in Material Studio 2017 using the GGA/PBE method with DNP basis, including the geometric structure and reaction pathway optimization, and adsorption energy calculation. All calculations were performed using a spin-polarized set and the TS method was used for DFT-D correction.