A Visible-Light-Active Heterojunction with Enhanced Photocatalytic Hydrogen Generation.
A visible-light-active carbon nitride (CN)/strontium pyroniobate (SNO) heterojunction photocatalyst was fabricated by deposition of CN over hydrothermally synthesized SNO nanoplates by a simple thermal decomposition process. The microscopic study revealed that nanosheets of CN were anchored to the surface of SNO resulting in an intimate contact between the two semiconductors. Diffuse reflectance UV/Vis spectra show that the resulting CN/SNO heterojunction possesses intense absorption in the visible region. The structural and spectral properties endowed the CN/SNO heterojunction with remarkably enhanced photocatalytic activity. Specifically, the photocatalytic hydrogen evolution rate per mole of CN was found to be 11 times higher for the CN/SNO composite compared to pristine CN. The results clearly show that the composite photocatalyst not only extends the light absorption range of SNO but also restricts photogenerated charge-carrier recombination, resulting in significant enhancement in photocatalytic activity compared to pristine CN. The relative band positions of the composite allow the photogenerated electrons in the conduction band of CN to migrate to that of SNO. This kind of charge migration and separation leads to the reduction in the overall recombination rate of photogenerated charge carriers, which is regarded as one of the key factors for the enhanced activity. A plausible mechanism for the enhanced photocatalytic activity of the heterostructured composite is proposed based on observed activity, photoluminescence, time-resolved fluorescence emission decay, electrochemical impedance spectroscopy, and band position calculations.
Department of Chemistry, Wake Forest University, Winston Salem, NC, 27109, USA.|Center for Energy, Environment and Sustainability (CEES), Wake Forest University, Winston-Salem, NC, 27109, USA.
Shiba P
0000-0001-6340-7471
SP
Adhikari
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.|School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
Zachary D
ZD
Hood
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.
Karren L
0000-0001-5223-9097
KL
More
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
Vincent W
VW
Chen
Department of Chemistry, Wake Forest University, Winston Salem, NC, 27109, USA. Lachgar@wfu.edu.|Center for Energy, Environment and Sustainability (CEES), Wake Forest University, Winston-Salem, NC, 27109, USA. Lachgar@wfu.edu.
Abdou
A
Lachgar
D002384:Catalysis; D003460:Crystallization; D006859:Hydrogen / Q000737:chemistry*; D008027:Light; D017348:Microscopy, Electron, Scanning Transmission; D055668:Photochemical Processes; D056951:Photoelectron Spectroscopy; D033362:Powder Diffraction; D013818:Thermogravimetry
D006859:Hydrogen
composite; heterojunction; hydrogen production; photocatalyst; water splitting