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

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. S-scheme mechanism of PEC water splitting with interfacial charge transfer in Bi2O2CO3/NiFe-LDH@g-C3N4. [Display omitted] •Bi2O2CO3/NiFe-LDH@g-C3N4 bifunctional photoelectrocatalyst synthesized with band gap 1.7 eV.•It shows low recombination rate of charge carriers, and faster HER and OER.•S-scheme mechanism associated interfacial charger transfer aided by Bi2O2CO3.