Journal Article

PUBDB-2023-07609

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Conductivity Mechanism in Ionic 2D Carbon Nitrides: From Hydrated Ion Motion to Enhanced Photocatalysis

Kröger, J. ; Podjaski, F. ; Savasci, G. ; Moudrakovski, I. ; Jiménez-Solano, A. ; Terban, M.Extern* ; Bette, S.Extern* ; Duppel, V. ; Joos, M. ; Senocrate, A. ; Dinnebier, R.Extern* ; Ochsenfeld, C. ; Lotsch, B. V. (Corresponding author)

2022
Wiley-VCH Weinheim

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Please use a persistent id in citations: doi:10.1002/adma.202107061  doi:10.3204/PUBDB-2023-07609

Abstract: Carbon nitrides are among the most studied materials for photocatalysis; however, limitations arise from inefficient charge separation and transport within the material. Here, this aspect is addressed in the 2D carbon nitride poly(heptazine imide) (PHI) by investigating the influence of various counterions, such as M = Li$^+$, Na$^+$, K$^+$, Cs$^+$, Ba$^{2+}$, NH$^{4+}$, and tetramethyl ammonium, on the material's conductivity and photocatalytic activity. These ions in the PHI pores affect the stacking of the 2D layers, which further influences the predominantly ionic conductivity in M-PHI. Na-containing PHI outperforms the other M-PHIs in various relative humidity (RH) environments (0–42%RH) in terms of conductivity, likely due to pore-channel geometry and size of the (hydrated) ion. With increasing RH, the ionic conductivity increases by 4–5 orders of magnitude (for Na-PHI up to 10-5 S cm$^{-1}$ at 42%RH). At the same time, the highest photocatalytic hydrogen evolution rate is observed for Na-PHI, which is mirrored by increased photogenerated charge-carrier lifetimes, pointing to efficient charge-carrier stabilization by, e.g., mobile ions. These results indicate that also ionic conductivity is an important parameter that can influence the photocatalytic activity. Besides, RH-dependent ionic conductivity is of high interest for separators, membranes, or sensors.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
2. DFG project 390776260 - EXC 2089: e-conversion (390776260) (390776260)

Experiment(s):

1. PETRA Beamline P21.1 (PETRA III)

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Wiley ; Essential Science Indicators ; IF >= 25 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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