Non-photochromic solar energy storage in carbon nitride surpassing blue radicals for hydrogen production

Abstract

Potassium poly(heptazine imide) (KPHI) exhibiting the dual functionality of photon absorption and photoelectron storage for solar energy conversion is a new class of ionic two-dimensional (2D) carbon nitrides. Rather than...

Optimizing the Optical Absorption of Poly(heptazine imide) by the n → π* Electron Transition for Improved Photocatalytic H2 Evolution

“…In any event, there is a significant difference in the XRD diffraction patterns in poly­(heptazine imide) and poly­(triazine imide). All of the poly­(heptazine imide) samples show a typical peak located around 8°, − and the poly­(triazine imide) shows a representative diffraction peak located around 11°, − which can be clearly observed in the previous research. In this work, the original PHI and RPHI samples exhibit a typical XRD diffraction peak located at 8.06°, indicating the poly­(heptazine imide) structure of the samples.…”

“…Noticeably, there is an obvious discrepancy with the previous research. 22,32,33 The NMR peak located around 120 ppm represents the cyano units (C�N). However, this peak does not appear in this work, and this may be related to the polymerization process of the sample.…”

Simultaneous Growth of the SnO2 Nanostructure and Phase Transformation of the Carbon Nitride Matrix by a Hydrothermal Process for Efficient Solar Hydrogen Evolution

“…Poly­(heptazine imide) (PHI) is an alternative carbon nitride composed of in-plane covalently imide-linked heptazine ring units. − This crystalline 2D heptazine-based carbon nitride with a highly conjugated PHI network demonstrates relatively fast charge transfer, which hinders the recombination of photogenerated electron–hole pairs . To configure the real 2D carbon nitride rather than the 1D melon structure, ionothermal treatment of a nitrogen-rich organic solid precursor or melon carbon nitride in appropriate salt melts is a commonly employed method, which produces the metal-intercalated PHIs.…”

“…Proton-exchanged counterpart (HPHI) can be further obtained by the post treatment of the metal-intercalated PHIs in the acid solution . The optimized PHI demonstrated a significant increase in the photocatalytic activity for H 2 evolution compared to the prototypical melon carbon nitride. − …”

NH-rich red poly(heptazine imide) nanoparticles with simultaneously promoted exciton dissociation and activated n → π* electronic transition for boosted photocatalytic H2 generation

“…38 Although CP/MAS is not suitable for quantitative analysis, the peak intensity ratios of C-N 2 -(NH x ) (C2) to C-N 3 (C3) in the 13 C NMR spectrum of the RPHIx NP are greater than those of PHI (Table S3 †), which is in agreement with the FTIR spectroscopy results of the NH-rich structure of the RPHIx NP. 39 Besides this, both PHI and the RPHIx NP show peaks at 11.0 and 4.5 ppm in their spectra (Fig. 3b), attributed to the H atoms in free water and amino groups.…”