Photoelectron Storages in Functionalized Carbon Nitrides for Colorimetric Sensing of Oxygen

Abstract

Colorimetric sensing has been widely used for centuries across diverse fields, thanks to easy operation with no electricity and uncompromised high sensitivity. However, the limited number of chromogenic systems hampers its broader applications. Here, we reported that carbon nitride (CN), the raw materials-abundant and cheap semiconductors with photoelectron storage capability, can be developed as a new chromogenic platform for colorimetric sensing. Beyond most photoelectron storage materials that only demonstrated blue color in the excited state, CN could also exhibit brown color by terminal group functionalization. The experiments and DFT theoretical calculation revealed the origin of the unusual two types of color switches. Cyano and carbonyl terminal groups in CN elongated the centroids distance of electron/hole and stabilized the excited states through a physical and electrochemical pathway, respectively; meanwhile, the counter cations strengthened these processes. As a result, the CN-derived colorimetric O2 sensors demonstrated excellent reversibility in recycling hundreds of times for detection, and exhibited adaptable limit of detection and linear detection range, which was superior to commercial O2 sensors, especially for complex systems with broad variable concentrations.

Effect of Functional Group Modifications on the Photocatalytic Performance of g‐C3N4

“…Han et al constructed a functionalized CN (CNK, CNNa) as a color development system for colorimetric sensors. [83] Compared with the conventional colorimetric system, CN showed multiple colors beyond the pure blue color of most photoelectron storage materials in the charged state. The FT-IR spectrum of functionalized CNK (Figure 7a) shows asymmetric stretching vibrations from 2150 to 2178 cm −1 , while the C 1s spectrum of CNK centered at 286.8 eV in XPS measurements (Figure 7b) demonstrates the presence of cyano-functional groups.…”

“…The charge separation properties of light generation were investigated by functionalizing the CTF with urea groups. [90] It was found that compared with CTF without urea functionalization, the addition of urea groups to CTF effectively inhibits [83] Copyright 2022, American Chemical Society.…”

“…c) UV-vis absorption spectra of CN, CNK, and CNNa. Reproduced with permission [83]. Copyright 2022, American Chemical Society.…”

Self-Adapting Graphitic C6N6-Based Copper Single-Atom Catalyst for Smart Biosensors

“…10 As a metal-free semiconductor, polymeric carbon nitride (PCN) has been intensively explored not only as a metal-free photocatalyst [11][12][13][14][15][16][17][18][19][20] but also as a solid ligand to anchor single metal atom, [21][22][23] owing to its engineerable conjugated repetitive units, rich lone pair electrons in the framework, and high physicochemical stability. For example, carbon nitrides with different topological structures (e.g., C3N4, C3N2, C5N2, and C2N) [24][25][26][27][28][29][30] and metal dopants (e.g., K and Cu) [31][32][33] have been developed for a wide range of photocatalytic oxidation reactions [34][35][36][37] (e.g., clean water and sanitation) and oxidase [38][39][40][41] /peroxidase-like [42][43][44] activities. Interestingly, these oxidation reactions are catalyzed by carbon nitrides via different reactive oxygen-related intermediates under similar conditions, except for light irradiation.…”

Colorimetric Sensor Based on Ag-Fe NTs for H2S Sensing

“…Colorimetric sensors have long been the focus of research studies due to their ability to perform simple, rapid, portable, low-cost, real-time, and nondestructive detection of analytes without complex instrumentation. Thus, colorimetric sensors are becoming widely used for safety and quality monitoring in a variety of industrial processes, such as bioanalytical chemistry, manufacturing, environmental, agriculture, warehousing, food safety, etc. − Colorimetric sensors aim to detect subtle changes by converting the relevant chemical or physical properties (i.e., temperature, pH value, or molecules) of molecular or ionic species into visible color changes that can be observed by the naked eye. Many efforts have therefore gone into the development of colorimetric sensor systems.…”