Morphology-modulated rambutan-like hollow NiO catalyst for plasma-coupled benzene removal: Enriched O species and synergistic effects.

[Display omitted] • Hollow spherical-shell NiO was prepared by a ligand modulation MOFs-derived method. • Hollow NiO improved benzene conversion and CO 2 selectivity, reducing energy consumption significantly. • Abundant surface O species of NiO are activated by plasma and thus induce superior catalytic ability. • Synergistic effect was clarified as NiO enhancing plasma field while plasma inspiring NiO oxidation ability. While catalyst morphology plays an essential role in traditional thermal catalysis, the specific effects in plasma catalysis deserve further in-depth study. In the present study, hollow NiO nanospheres with a rambutan-like structure were successfully prepared by MOFs-derived method involving morphology modulation, and employed for the in-plasma catalytic oxidation of benzene. The results show an enhancement of 60 % for benzene removal, while CO 2 selectivity was increased by 20 %. The energy consumption for 95 % benzene removal efficiency (RE 95%) was also reduced from 3600 J/L to 1100 J/L. Specifically, the hollow spherical shell structure is more abundant in surface oxygen species, including chemisorbed oxygen and surface lattice oxygen, which can be activated by plasma; the hollow structure also modulates the plasma discharge by shielding effect. The plasma field in turn also excites the oxidation activity of NiO, thus achieving the synergistic effect. In addition, a more comprehensive benzene decomposition pathway is proposed by analysis of the gaseous and non-gaseous intermediates (tar), where the plasma non-selectively breaks the chemical bonds of reactants and the catalyst selectively oxidizes the organic intermediates to CO 2 , and they promote each other to achieve synergistic effects. [ABSTRACT FROM AUTHOR]