Structural Band-Gap Tuning in g-C₃N₄

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Abstract

g-C3N4 is a promising material for hydrogen production from water via photo-catalysis, if we can tune its band gap to desirable levels. Using a combined experimental and ab initio approach, we uncover an almost perfectly linear relationship between the band gap and structural aspects of g-C3N4, which we show to originate in a changing overlap of wave functions associated with the lattice constants. This changing overlap, in turn, causes the unoccupied pz states to experience a significantly larger energy shift than any other occupied state (s, px, or py), resulting in this peculiar relationship. Our results explain and demonstrate the possibility to tune the band gap by structural means, and thus the frequency at which g-C3N4 absorbs light.

Description

Supplementary materials available.

Keywords

Photonic band gap, Graphitic Carbon Nitride (g-C3N4), Lattice constants, Hydrogen, Light absorption

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"This work was supported by Department of Energy Grant No. DE-FG02-08ER46491. NS, who performed the XRD measurements, was supported by DOE grant No. DE-SC0010697."

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©2015 The Owner Societies

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