Bismuth oxycarbonate grafted NiFe-LDH supported on g-C3N4 as bifunctional catalyst for photoelectrochemical water splitting

Abstract

In the present study, we report the synthesis of photoactive bismuth oxycarbonate (BOC, Bi2O2CO3) grafted NiFe layered double hydroxide (LDH) supported on g-C3N4 (15 wt% of g-C3N4) by coprecipitation method. The band gap of this photoactive material is determined to be 1.7 eV. The Bi2O2CO3 agglomerates are anchored on NiFe-LDH plates and g-C3N4 nanosheets intercalated between the LDH plates. This architecture helps in expediting electron transfer for hydrogen and oxygen evolution reactions. The pristine NiFe-LDH photoanode acquires bifunctional character because of Bi2O2CO3 agglomerates and g-C3N4 embedded in the architecture of BOC/NiFe-LDH@g-C3N4. This is found to be an efficient photoanode for oxygen evolution and photocathode for hydrogen evolution reactions. The water splitting process occurs along the heterojunction formed between g-C3N4 nanosheets and Bi2O2CO3 grafted NiFe-LDH. Further, an additional interfacial charge transfer aided by Bi2O2CO3 results in S-scheme mechanism, which enhances the rate of photoelectrochemical hydrogen and oxygen evolution reactions.