Pd 2 and CoPd dimers/N-doped graphene sensors with enhanced sensitivity for CO detection: A first-principles study

Context The detection and monitoring of CO gas are essential to avoid human health problems. Therefore, the CO adsorption on Pd 2 and PdCo dimers deposited on pyridinic N x -doped graphene (PN x G; x = 1 – 3) was investigated employing the auxiliary density functional theory. In the most stable arrangements for the Pd 2 dimer supported on PN x G, a Pd atom is in the PN x G vacancy, and the other Pd atom is placed on C atoms. For the PdCo dimer deposited on PN x G, the most stable interaction is like Pd 2 dimer supported on PN x G, but with the Co atom centered over the vacancy site. Concerning the stability of the Pd 2 and PdCo dimers supported on PN x G, the interaction energies (E int ) of the PdCo dimer deposited on PN x G are higher than those obtained with the Pd 2 dimer. Also, the E int of Pd 2 and PdCo dimers deposited on PN x G are higher than those supported on pristine graphene. The CO adsorption energies on Pd 2 /PN x G and PdCo/PN x G composites are higher than those reported in the literature for pristine graphene, showing that the Pd 2 /PN x G and PdCo/PN x G composites have a good sensitivity toward the CO molecule. Methods All electronic structure calculations were performed using the auxiliary density functional theory implemented in the deMon2k program. For exchange and correlation functional, the revised PBE was used. The Pd atoms were treated with an 18-electron QECP|SD basis set, while the remaining atoms were subjected to a DZVP-GGA basis set. The GEN-A2* auxiliary-function-set was used for all computations.