Bifunctional Modification of Graphitic Carbon Nitride with MgFe₂O₄ for Enhanced Photocatalytic Hydrogen Generation

Abstract

To gain high photocatalytic activity for hydrogen evolution, both charge separation efficiency and surface reaction kinetics must be improved, and together would be even better. In this study, the visible light photocatalytic hydrogen production activity of graphitic carbon nitride (g-C3N4) was greatly enhanced with MgFe2O4 modification. It was demonstrated that MgFe2O4 could not only extract photoinduced holes from g-C3N4, leading to efficient charge carrier separation at the g-C3N4/MgFe2O4 interface, but also act as an oxidative catalyst accelerating the oxidation reaction kinetics at g-C3N4 surface. This dual function of MgFe2O4 thus contributed to the great improvement (up to three-fold) in photocatalytic activity for hydrogen generation over g-C3N4/MgFe2O4 as compared to pristine g-C3N4, after loading Pt by photoreduction method. It was revealed that in the Pt/g-C3N4/MgFe2O4 system, the photoinduced electrons and holes were entrapped by Pt and MgFe2O4, respectively, giving rise to the promoted charge separation; moreover, as evidenced by electrochemical analysis, the electrocatalysis effect of MgFe2O4 benefited the oxidation reaction at g-C3N4 surface.

One‐Step Synthesis of Nb2O5/C/Nb2C (MXene) Composites and Their Use as Photocatalysts for Hydrogen Evolution

“…Electrochemical impedance spectroscopy (EIS) was performed to elucidate the charge‐transfer resistance in the photocatalyst. In particular, a smaller radius of the arc in the spectra indicates a smaller electron‐transfer resistance on the surface of the photoelectrodes, which normally leads to more effective separation of the photoelectron–hole pairs and faster interfacial charge transfer . As shown in Figure A, the arc radius of the EIS Nyquist plots of NCN‐1.0 is clearly smaller than that of Nb 2 CT x , probably as a result of substantial removal of the functional groups and intercalated water molecules during the oxidation process at high temperature .…”

“…In particular,asmallerr adius of the arc in the spectra indicates asmaller electron-transfer resistance on the surface of the photoelectrodes, which normally leads to more effective separation of the photoelectron-holep airs and faster interfacial charge transfer. [44,53] As shown in Figure 8A,t he arc radius of the EIS Nyquistp lotso fN CN-1.0 is clearly smaller than that of Nb 2 CT x ,p robablya sar esult of substantial removal of the functional groups and intercalated water molecules duringt he oxidation process at high temperature. [34] The EIS Nyquist plots can be simulated to the equivalent electrical circuit shown in Figure 8A (inset), in which R s and R t are the electrolyte solution resistance and the interfacial charge-transfer resistance/electrolyte, respectively,a nd CPE is the constant phase element.…”

Novel carbon-incorporated porous ZnFe2O4nanospheres for enhanced photocatalytic hydrogen generation under visible light irradiation

“…[6][7][8][9][10] In particular, n-type semiconductor zinc ferrite (ZnFe 2 O 4 ) with a typical E g of about 1.9 eV show effective absorption of sunlight, high photochemical stability, high catalytic activity, good durability and low cost. Despite this, the photocatalytic activity of individual ZnFe 2 O 4 nanoparticles is pretty poor due to the rapid recombination of photogenerated charge and the large scale aggregation of nanoparticles with the ferromagnetic property.…”

Artificial Photosynthesis with Polymeric Carbon Nitride: When Meeting Metal Nanoparticles, Single Atoms, and Molecular Complexes

“…(CB: CB, VB: VB, MFO: MgFe 2 O 4 , and TEOA: triethanolamine). Reproduced with permission, Copyright 2015, American Chemical Society. b) Schematics of band structure and charge transfer process in Pt/N‐CeO x /PCN for photocatalytic hydrogen generation.…”