Semiconducting polymeric carbon nitride (CN) has drawn wide attention ranging from photocatalysis to more recent biosensing owing to unique defect‐tolerated optoelectronic properties and being metal‐free, cheap, and highly stable. However, at the core of electrical–optical interconversion, the preparation of the CN photoelectrode is still challenging. Now, the growth of CN on electrodes is achieved simply by microwave‐assisted condensation in seconds. The ultrafast heating not only addressed the thermodynamic contradiction of precursor volatilization during polymerization but also led to strongly adhesive CN layer on electrodes with gradient carbon‐rich texture, greatly accelerating the electron–hole separation and mobility. Consequently, the CN photoelectrode exhibited a remarkable photocurrent and a record cathodic efficiency of electrochemiluminescence up to 7 times that of benchmark Ru(bpy)3Cl2 in aqueous solution.
Artificial photocatalysis offers a clean approach for producing H2O2. However, the poor selectivity and activity of H2O2 production hamper traditional industrial applications and emerging photodynamic therapy (PDT)/chemodynamic therapy (CDT). Here, we report a well-defined C5N2 photocatalyst with a conjugated C=N linkage for highly selective and efficient non-sacrificial H2O2 production both in normoxic and hypoxic systems. The strengthened delocalization of −electrons by linkers in C5N2 significantly downshifted the band position, which eliminated the side photoreduction reaction of H2 evolution in thermodynamics and promoted water oxidation ability in kinetics. As a result, C5N2 had a competitive overall H2O2 production with solar-tochemical conversion efficiency of 0.55% and more interestingly, exhibited the highest activity so far in hypoxic condition (698 M/h). C5N2 was further applied to hypoxic PDT/CDT, exhibiting outstanding performance in conspicuous cancer cell death and synchronous bioimaging. It shed light on unlocking linker functions in electronic structure engineering of carbon nitrides for highly efficient overall photosynthesis of H2O2 and expanded the scope of their prospective application in health care.
Semiconducting polymeric carbon nitride (CN) has drawn wide attention ranging from photocatalysis to more recent biosensing owing to unique defect‐tolerated optoelectronic properties and being metal‐free, cheap, and highly stable. However, at the core of electrical–optical interconversion, the preparation of the CN photoelectrode is still challenging. Now, the growth of CN on electrodes is achieved simply by microwave‐assisted condensation in seconds. The ultrafast heating not only addressed the thermodynamic contradiction of precursor volatilization during polymerization but also led to strongly adhesive CN layer on electrodes with gradient carbon‐rich texture, greatly accelerating the electron–hole separation and mobility. Consequently, the CN photoelectrode exhibited a remarkable photocurrent and a record cathodic efficiency of electrochemiluminescence up to 7 times that of benchmark Ru(bpy)3Cl2 in aqueous solution.
Facile evaluation of oxygen reduction reaction (ORR) kinetics for massive electrocatalysts is critical for sustainable fuel cells development and industrial H2O2 production. Despite great success in ORR studies by mainstream strategies, such as membrane electrode assembly, rotation electrode technique and advanced surfacesensitive spectroscopy, the time/spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer is still unknown. By time-dependent electrochemiluminescence (Td-ECL), here we report an intermediate-oriented methodology for ORR kinetics analysis. Thanks to multiple ultra-sensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential-dependent time/spatial distribution of ROS was successfully obtained for the first time. Such uncovered exclusive information would guide fuel cells and H2O2 production with maximized activity and durability, for instance, a larger overpotential would be beneficial to electrocatalysts of 2e − reduction for H2O2 production, because of the high yield of H2O2 and low concentration of attackable O2 •− . This work would pave the exploration of not only the fundamentals of unambiguous ORR mechanism but also the durability of electrocatalysts for practical applications.
The fabrication of carbon dots and their doped forms by top‐down chemical cleavage has attracted considerable attention in the efforts to meet the increasing demands for optoelectronic applications ranging from biosensing to electro‐ and photocatalysis. However, due to strong quantum confinement effects, the size decrease often leads to an increase in the band gap, even in the emission of deep‐ultraviolet (DUV) light, which greatly limits their applications. Here, we report a facile hot‐tailoring strategy for fabricating carbon nitride nanodots (CNDs) with redshifted intrinsic photoluminescent (PL) emission, compared with the pristine bulk precursor. It has been found that the different leaving abilities of the C,N‐containing groups during the pyrolysis stage and the chemical passivation during the liquid‐collection stage played vital roles. Due to the redshifted photoluminescence and other attractive features, the as‐obtained CNDs were successfully applied in visual double text encryption with higher security and also in bioimaging with photostability superior to traditional dyes. This work highlights the great potential of the hot‐tailoring method in modulating carbon‐based nanostructures and offsetting band‐gap widening as the size decreases.
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