Catalysis of the acetylene hydrochlorination reaction by Si-doped Au clusters: a DFT study

The mechanisms for the acetylene hydrochlorination reaction on pristine Au₇ and Au₈ clusters and on the Si-doped Au clusters Au₆Si and Au₇Si were systematically investigated via density functional theory using the PBE functional. The band gap (∆E_g) of the Au₇Si cluster was found to smaller than that of its undoped equivalent (Au₈), thus enhancing its catalytic activity, and Au₇Si presented a significantly reduced activation barrier (16.69 kcal mol^-1) for the acetylene hydrochlorination reaction compared with the pristine Au₈ cluster (21.83 kcal mol^-1). On the other hand, the activation barrier for the acetylene hydrochlorination reaction was not lower for the Au₆Si cluster than for the pristine Au₇ cluster because the band gap (∆E_g) of Au₆Si was found to be larger than that of Au₇. Hence, the current work shows that the catalytic activities of gold clusters can be systematically modified by doping them. Our findings also suggest how to enhance the acetylene hydrochlorination reaction by doping foreign atoms into Au clusters. Graphical abstract The Si-doped Au₇Si cluster showed stronger catalytic activity for the acetylene hydrochlorination reaction compared with the pristine Au₈ cluster.