SF

6

degradation mechanism in non-thermal plasma (NTP) systems is not fully understood due to the formation of a complex physico-chemical reaction network

especially when reactive gases and packing materials are involved. In this work

we conduct a combined experimental and theoretical study to unravel the SF

6

degradation path in a γ-Al

2

O

3

packed plasma in the presence of H

2

O or O

2

. Our experimental results show that both H

2

O and O

2

have a synergetic effect with γ-A1

2

O

3

packing on promoting SF

6

degradation

leading to higher stable gas yields than typical spark or corona discharges. HO or O

2

addition promotes SO

2

or SO

2

F

2

selectivity

respectively. Density functional theory (DFT) calculations reveal that SO

2

generation corresponding with the highest activation barrier is the most critical step toward SF

6

degradation. Radicals like H and O generated from H

2

O or O

2

discharge can significantly promote the degradation process via Eley-Rideal mech

anism

affecting key reactions of stable product generation

advancing degradation efficiency. The results of this work could provide insights on further understanding SF

6

degradation mechanism especially in packed-bed plasma systems.