In double dielectric barrier discharge aqueous electrodes reactor(DDBD)

hydrogen peroxide was prepared in a mixture of hydrogen and oxygen by using DBD discharge with inert gas(Ar

He and N2)as additive gas.The influence of different inert gases on the breakdown voltage and energy efficiency of H2O2 synthesis was studied.The results showed that breakdown voltage

conversion of O2

selectivity of H2O2

yield of H2O2 and energy efficiency were obviously affected by different inert gases.The breakdown voltage could be reduced with He and Ar as additive gas

however

it became higher when N2 was the additive gas.On the other hand

energy efficiency of H2O2 synthesis was reduced dramatically with N2 as the additive gas

and little changed with He as the additive gas.However

energy efficiency of H2O2 synthesis increased markedly with Ar as the additive gas.When Ar flow rate was 56.6 ml穖in-1

breakdown voltage could be reduced from 11.8 kV to 10.2 kV;energy efficiency of H2O2 synthesis increased by about 51%

from 3.45 g?(kW穐)-1 to 5.20 g?(kW穐)-1(100% H2O2).Therefore

the addition of Ar could not only reduce breakdown voltage

but also increase energy efficiency of H2O2 synthesis.The optical emission spectra revealed that Penning ionization effects of metastable state Ar species(696.5

794.8

811.5 nm)existing in H2-O2-Ar discharge system might be responsible for the decrease of breakdown voltage.From the waveform of discharge current

the addition of Ar increased electron density

which obviously facilitated the increase of O2 conversion and energy efficiency of H2O2 synthesis at the same power.