Protonation-induced site and field reconstruction for ultrafast adsorptive desulfurization over Cu-N-C

Abstract Simultaneously manipulating adsorption thermodynamics/kinetics and site density to realize the efficient adsorption capability of single-atom materials was important for adsorption-related catalysis, separation or purification, but remained challenging. Taking adsorptive desulfurization as a model, we reported a simple protonation of pyridinic-N strategy that notably improved the adsorption capability of Cu-N-C for dibenzothiophene via the cation-π and Cu-S interaction. The pyridinic-NH + both acted as adsorption site and modulated the N-ligand field to elongate Cu-N bond to enhance the bonding strength of single-atom Cu site for organosulfur via upshifting the d-band center, thereby causing a higher desulfurization capacity of Cu-N-C than its counterparts. Moreover, the protonation reconstructed the surface electric field of Cu-N-C to weaken the repulsion effect between Cu-N-C and dibenzothiophene, which along with the abundant porous channel accelerated mass transfer and accumulation of dibenzothiophene around adsorption sites. This endowed Cu-N-C with a 2.4~310-fold higher adsorption kinetics than most reported adsorbents, thus achieving a ultrafast decrease of sulfur level (<10 ppm) within 70s, notably outstripping that of Fe-N-C (~ 900s) and activated carbon (~ 1800s).