Carbon defects in graphitic carbon nitride (g-CN) can modulate the electronic structure for efficient separation of electron–hole pairs, and thereby potentially enhance the photocatalytic H 2 generation. However, the mechanism on the separation of electrons and holes in C defect-modified g-CN still remains unclear. Here we report an autogenic ammonia gas route via in-situ urea decomposition to create carbon defects in g-CN for realizing increased photocatalytic H 2 generation rate of 36.62 µmol h −1 under visible light exposure, which is 10 times higher than that of g-CN obtained in the absence of autogenic ammonia gas (~ 3.63 µmol h −1 ). Illustrated by the density functional theory calculations, the C defects can not only reduce the band gap for increased light harvesting, but also delocalize the π electrons in valence band (VB) and conduction band (CB) for efficient charge transfer. Such delocalization of π electrons facilitates the efficient separation of electrons in LUMO and holes in HOMO, then promoting the photocatalytic H 2 generation. Therefore, the creation of C defects can be used as an effective route to delocalize the π electrons in g-CN for efficient photocatalytic H 2 generation. Graphical Abstract
Peipei Zhang,Haibing Zhang,Sufen Cui,Zhimin Jiang,Jun Yang,Minjie Shi
The emergence of hybrid capacitive deionization (HCDI), utilizing faradaic electrodes with pseudocapacitive properties, offers a promising electrochemical solution for water desalination and purification. Despite the increasing interest in organic materials for faradaic electrodes, their widespread use in HCDI devices is still hindered by obstacles about insufficient redox-active sites and low stability in aqueous environments. To address these challenges, we introduce a novel dual-functional redox-active polymer, named PZPS, which features a rigid conjugated backbone with dual-redox centers (C N and S O bonds). This unique molecular design, along with extensive π-electron delocalization across the strong polymeric structure, significantly improves pseudocapacitive Na + coordination and ensures remarkable stability in aqueous solution. As an electrode, the PZPS polymer exhibits an impressive specific capacitance and excellent cyclability, maintaining 98.04 % of its initial capacitance after 10,000 cycles. Consequently, a high-performance HCDI device with the PZPS electrode demonstrates impressive electrochemical desalination capabilities. It achieves a substantial salt removal capacity of 58.82 mg g −1 at 1.2 V, a rapid average removal rate of 1.96 mg g −1 min −1 , and remarkable regeneration stability (∼93.15 % after 50 cycles). These results highlight the electrochemical advantages of the PZPS-based HCDI device and underscore its significant potential for highly efficient desalination applications.
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