<i>In situ</i> textured carbon nitride photoanodes with enhanced photoelectrochemical activity by band-gap state modulation

Huang, Miaoyan; Wang, Haipeng; Li, Wan; Zhao, Yanling

doi:10.1039/d0ta06550a

Cited by 12 publications

(8 citation statements)

References 36 publications

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“…[19,20] The PEC performance of CNbased materials is currently hindered by three main limitations: 1) moderate light-harvesting properties; 2) the poor charge separation and transfer efficiency of unmodified CN; and 3) slow oxygen evolution reaction (OER, i.e., water oxidation) kinetics. [21][22][23] Recently, several studies have shown how the optical and electronic properties of CN materials may be modified by using alkaline metal cations (K and Na) [24][25][26] and heteroatoms (such as B, [27] S, [28] O, [29] and P [30] ) as dopants. Alkaline metal ions improve the separation and transfer of photoexcited charge carriers by forming coordinative bonds with N atoms in the CN lattice.…”

Section: Introductionmentioning

confidence: 99%

Boron and Sodium Doping of Polymeric Carbon Nitride Photoanodes for Photoelectrochemical Water Splitting

Shmila,

Mondal,

Barzilai

et al. 2023

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Polymeric carbon nitride is a promising photoanode material for water‐splitting and organic transformation‐based photochemical cells. Despite achieving significant progress in performance, these materials still exhibit low photoactivity compared to inorganic photoanodic materials because of a moderate visible light response, poor charge separation, and slow oxidation kinetics. Here, the synthesis of a sodium‐ and boron‐doped carbon nitride layer with excellent activity as a photoanode in a water‐splitting photoelectrochemical cell is reported. The new synthesis consists of the direct growth of carbon nitride (CN) monomers from a hot precursor solution, enabling control over the monomer‐to‐dopant ratio, thus determining the final CN properties. The introduction of Na and B as dopants results in a dense CN layer with a packed morphology, better charge separation thanks to the in situ formation of an electron density gradient, and an extended visible light response up to 550 nm. The optimized photoanode exhibits state‐of‐the‐art performance: photocurrent densities with and without a hole scavenger of about 1.5 and 0.9 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE), and maximal external quantum efficiencies of 56% and 24%, respectively, alongside an onset potential of 0.3 V.

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Section: Introductionmentioning

confidence: 99%

Boron and Sodium Doping of Polymeric Carbon Nitride Photoanodes for Photoelectrochemical Water Splitting

Shmila,

Mondal,

Barzilai

et al. 2023

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“…[14][15][16]. Currently, among diverse in-situ PCN film growth approaches including thermal vapor condensation (TVC) [17][18][19][20][21], molten-mediated method [22][23][24][25], doctor-blade method [26][27][28], and electrophoretic deposition method [29], the molten-mediated method exhibits great potential for growing robust and high-quality PCN films [22,23]. The first report of the molten-mediated method for PCN film employed molten sulfur as a co-melting medium to improve mass transfer and promote PCN polymerization [24].…”

Section: Introductionmentioning

confidence: 99%

Integrated molten and vapor condensation of polymeric carbon nitride photoelectrode towards efficient water splitting

Wang

Tan

et al. 2022

Sci. China Mater.

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Polymeric carbon nitride (PCN) has received extensive attention in suspension photocatalysis, whereas the preparation of high-quality PCN film is still at an initial stage, limiting its practical application in photoelectrochemical (PEC) systems. Herein, an integrated molten and vapor condensation route is realized using small molecule precursors dicyandiamide (DCDA) and thiourea (TU) to form PCN film photoelectrode with high performance. The in-situ deposition route endows the PCN film with a composite structure including a thick porous zone with suitable thickness for light absorption and thin compact zone with a higher C/N ratio for better charge transportations. The growth of the specific film and the functions of precursors DCDA and TU are investigated in detail. Owing to the unique condensation route and film structure, this PCN film exhibits excellent performance in PEC water splitting with a photocurrent density of ca. 140 μA cm −2 in 0.1 mol L −1 NaOH electrolyte at 1.23V RHE , which is competitive or higher than the results of the reported PCN photoanodes prepared by the molten-mediated method and thermal vapor condensation. The integrated molten and vapor condensation strategy is enlightening for comprehending the growth of PCN photoelectrodes.

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“…Doping through covalent functionalization, that is, forming chemical bonding with dopants, is often utilized to alter the bandgap states and thus physicochemical properties of functional materials. Our group has doped B, [14] O, [15] and S [16] heteroa toms into g-CN thin films by means of covalent functionalization, and has successfully improved the photocurrent densities with broadened range of light absorption. [17] Charge transfer resulted from the surface functionalization can possibly enhance the charge separation and reduce the probability of carrier recombination.…”

Section: Introductionmentioning

confidence: 99%

Charge Transfer Doping of Carbon Nitride Films through Noncovalent Iodination for Enhanced Photoelectrochemical Performance: Combined Experimental and Computational Insights

Tian

Zhao

et al. 2022

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To improve the photoelectrochemical (PEC) performance of photocatalysts, the doping strategy through covalent functionalization is often adopted to adjust material electronic structures. By contrast, this work demonstrates that the noncovalent interaction in the case of iodinated graphitic carbon nitride (g‐CN) film can also enhance the PEC performance. Through a facile synthesis method of rapid thermal vapor condensation (RTVC), the prepared iodinated g‐CN film shows a significantly improved photocurrent density (38.9 µA cm−2), three times that of pure g‐CN film (13.0 µA cm−2) at 1.23 V versus reversible hydrogen electrode. Computations reveal that the noncovalent attachment of iodine anion (I−) on g‐CN plays a crucial role in modulating the bandgap states and broadening of the visible‐light absorption range as well as the charge carrier separation with the photo‐induced hole confined to I− and electron to g‐CN film. The fully filled valence orbitals (4d105s25p6) of I− determine its noncovalent attachment on the g‐CN film and so do the iodine species of I3−, I5−, etc. This work offers a favorable synthesis method to achieve efficient doping through noncovalent charge transfer between thin film and certain dopants and provides a useful modification strategy for the establishment of multi‐channel transportation of charge carriers in general photocatalysts.

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In situ textured carbon nitride photoanodes with enhanced photoelectrochemical activity by band-gap state modulation

Abstract: Carbon nitride (CN) films have emerged as promising photoelectrodes in photoelectrochemical (PEC) water splitting cells. However, due to its intrinsic poor charge transfer dynamics and the absence of a controllable...

Cited by 12 publications

References 36 publications

Boron and Sodium Doping of Polymeric Carbon Nitride Photoanodes for Photoelectrochemical Water Splitting

Boron and Sodium Doping of Polymeric Carbon Nitride Photoanodes for Photoelectrochemical Water Splitting

Integrated molten and vapor condensation of polymeric carbon nitride photoelectrode towards efficient water splitting

Charge Transfer Doping of Carbon Nitride Films through Noncovalent Iodination for Enhanced Photoelectrochemical Performance: Combined Experimental and Computational Insights

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