Photochemical and electrochemical reduction of graphene oxide thin films: tuning the nature of surface defects

Abstract

Tuning the reduction degree and the nature of surface defects (vacancies, sp3) in rGO upon combined mild photo(electro)chemical reduction.

Effect of Electrolytic Medium on the Electrochemical Reduction of Graphene Oxide on Si(111) as Probed by XPS

“…It can be appreciated that more oxygen-containing functional groups were removed during the reduction in the non-aqueous medium (R O/C = 0.20) compared to the aqueous one (R O/C = 0.60). The R O/C value obtained for the erGO non-aq sample is lower than the ones previously reported for electrochemically reduced GO in an acidic medium (R O/C = 0.26) and in a proton-free organic electrolyte (R O/C = 0.56) [ 18 ], and approximately the same as that obtained from combined electrochemical and photochemical routes (R O/C = 0.21) [ 19 ] and from chemical, biological and thermal-based reduction approaches [ 5 ].…”

“…It can be appreciated that in both aqueous and non-aqueous media, three of the four resulting peaks ( i to iii ) exhibited a very important contribution to the voltammetric wave. Such features probably represent a very specific stage of the electrochemical reduction process, which is not a straightforward matter to assign [ 10 , 18 , 19 , 41 , 63 ]. Based on the relative stability of each of the OFGs, one can expect that a possible reduction sequence would be as follows: epoxy, carbonyl, hydroxyl then carboxyl.…”

“…As to the carboxyl abatement in an organic medium, this is an unprecedented result considering the use of an electrochemical reduction route. Though no explicit electrochemical features corresponding to COOH reduction could be identified in the voltammogram related to the erGO non-aq sample, it is likely that this process may have partially been shaded by the solvent decomposition occurring below −2.7 V. The abatement of carboxyl groups turns out to be particularly relevant due to their reported negative role in the voltammetric response of the resulting erGO materials [ 19 ].…”

“…In fact, it can be reduced (or partly reduced) to graphene-like sheets by removing the OFGs [ 17 ]. The rGO sheets are typically considered to be a material with intermediate properties compared to GO and pristine graphene [ 17 , 18 , 19 ], whereas fully reduced GO has properties very close to graphene [ 9 ]. In recent years, due to its unique properties such as its hydrophilic character, tunable optical band gap and high chemical reactivity, GO has received much attention for its technological implementation [ 15 , 19 , 20 , 21 ].…”

“…The rGO sheets are typically considered to be a material with intermediate properties compared to GO and pristine graphene [ 17 , 18 , 19 ], whereas fully reduced GO has properties very close to graphene [ 9 ]. In recent years, due to its unique properties such as its hydrophilic character, tunable optical band gap and high chemical reactivity, GO has received much attention for its technological implementation [ 15 , 19 , 20 , 21 ]. In fact, GO has been applied in electronic gate dielectric materials, such as thin film transistors and resistive random-access memory, solar cells and biosensors.…”