Competitive adsorption of water and chemical warfare agents on transition metal embedded graphene

Adsorption of three CWA molecules (soman, sarin and mustard gas) was systematically explored on transition metal (Chromium and Vanadium) embedded graphene models under dry and wet conditions. Density Functional Theory calculations first revealed that both metal@graphene substrates show a very high affinity for all CWAs under dry conditions, sarin being expected to be even more strongly coordinated since its associated adsorption energies above 43 kcal.mol(-1) are higher than the values calculated for soman and mustard gas. Two different wet scenarios were further explored with the consideration of a pre-humidification and a simultaneous competitive adsorption of water with CWAs. These calculations evidenced that the presence of water decreases the CWA adsorption energy for sarin and soman in the two embedded graphene models by maximum 20%. Interestingly, we demonstrated that this decrease is much less pronounced (3.3%) in the case of gas mustard adsorbed on chromium embedded graphene. Such metal embedded carbon substrates are thus predicted to maintain globally high level of CWA capture performances under humidity which corresponds to the most common operating conditions of protective gas masks. An In-depth analysis of the interactions between the CWAs and the metal embedded graphene in the presence of water was further conducted to gain insight into the origin of this energetic trend at the electronic-level.