Efficient Electronic Modulation of g-C ₃ N ₄ Photocatalyst by Implanting Atomically Dispersed Ag ₁ -N ₃ for Extremely High Hydrogen Evolution Rates

Abstract

Open AccessCCS ChemistryRESEARCH ARTICLE5 Aug 2022Efficient Electronic Modulation of g-C3N4 Photocatalyst by Implanting Atomically Dispersed Ag1-N3 for Extremely High Hydrogen Evolution Rates Guanchao Wang†, Ting Zhang†, Weiwei Yu†, Zhe Sun†, Xiaowa Nie, Rui Si, Yuefeng Liu and Zhongkui Zhao Guanchao Wang† State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 , Ting Zhang† State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 , Weiwei Yu† State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 , Zhe Sun† State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 , Xiaowa Nie State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 , Rui Si *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 , Yuefeng Liu *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Dalian National Laboratory for Clean Energy (DNL), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 and Zhongkui Zhao *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 https://doi.org/10.31635/ccschem.021.202101191 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Developing an efficient method to improve the photocatalytic efficiency of graphitic carbon nitride (g-C3N4) is of great significance for solar H2 production. Electronic structure modulation has been considered one of the most crucial strategies to improving the photocatalytic efficiency of g-C3N4, but how to efficiently modulate its electronic structure remains a huge challenge. Herein, we, for the first time, report a facile and highly-efficient approach to modulating the electronic structure of g-C3N4 through single Ag atom implantation with a Ag1-N3 coordination configuration into the g-C3N4 framework. Due to the remarkably promoted light absorption and notably improved charge separation resulting from efficient electronic structure modulation, the Ag1-N3 sites embedded hollow g-C3N4 sphere (Ag1N3-HCNS) shows an unprecedentedly high visible-light photocatalytic H2 evolution rate (HER) of 17.95 mmol g−1 h−1 under an atmospheric pressure with a remarkable apparent quantum yield (AQY) of 23.6% at 420 nm. Owing to different test apparatuses and conditions in different literature, neither the absolute HER value nor AQY could be used as a comparative indicator. Generally, times (tsHER) regarding the improvement in HER compared to bulk g-C3N4 under the same test apparatus and conditions are presented in the literature. Therefore, the tsHER can be used as an indicator for comparisons of the photocatalytic performance of the developed catalyst. Ag1N3-HCNS shows an unprecedented 193-fold higher HER than bulk g-C3N4 under the same measurement conditions, remarkably outperforming the previously reported g-C3N4 photocatalysts. This work presents a new horizon for designing excellent g-C3N4 photocatalysts through efficient electronic structure modulation of tri-s-triazine by implanting single-atom metals with strong metal-N bonding. Download figure Download PowerPoint Introduction Hydrogen is a promising second energy source and considered an important key building-block material in many modern chemical processes, such as Fischer–Tropsch synthesis and ammonia reactions.1 Solar photocatalytic water splitting into hydrogen fuels has been considered a promising strategy to alleviate the growing energy crisis and environmental challenges caused by fossil fuel burning.1–4 To realize the practical applications concerning green hydrogen production via photocatalytic water splitting, intense efforts have been devoted to designing more active photocatalysts and systems.5–7 Recently, a variety of semiconductors have been reported for water splitting.8–10 Among them, graphitic carbon nitride (g-C3N4) has attracted more attention due to its low cost precursor, suitable band gap, unique N/C coordinating network consisting of a tri-s-triazine structure, high physical and chemical stability, and good optical electronic structure.11–15 However, bulk C3N4 (BCN) still suffers from inferior photocatalytic efficiency owing to its low charge separation and transfer, insufficient light absorption, and low specific surface area, limiting its further development.16,17 Aimed at compensating for the intrinsic drawbacks of g-C3N4 to enhance its photocatalysis, many strategies like nanostructure design, electronic structure modulation, crystal-structure engineering, and heterostructure construction have been developed,16,18–21 among which electronic structure modulation can be considered as one of the most crucial and effective approaches to improving the photocatalytic efficiency of g-C3N4.20,22–24 Although many efforts to modulate the electronic structure of g-C3N4 to improve its photocatalysis have been made,20,22–29 the development of a facile and efficient electronic regulation method remains a sizable challenge. From references,20,30,31 compared to non-metallic element doping, metal element-doping has emerged as a promising approach for the electronic modulation of g-C3N4. Unfortunately, the incorporation of metal nanoparticles (NPs) has not worked well thus far. It is highly desirable to develop a facile and efficient method for electronic structure regulation via metal element-doping of g-C3N4. Recently, single-atom metals (SAMs), as catalytically active sites to lower the H2 evolution energy barrier, have attracted great interest in g-C3N4 photocatalysis.32–37 Although the H2 evolution rate (HER) per gram metal is efficiently improved owing to atomic dispersion, the HER per gram g-C3N4 catalyst remains quite low. To achieve ultrahigh loading of SAM remains a challenge. Now that the doping of metal NPs can effectively adjust the electronic structure of g-C3N4, the implantation of SAM could be proposed as a sophisticated strategy for electronic modulation to improve the HER per gram g-C3N4 catalyst. However, nowadays, rare reports on the SAM-doping of g-C3N4 regarding the modulation of electronic structures can be found. From references,38–41 the implantation of SAM via strong covalent metal-N bonding is more efficient than that by a weak electrostatic interaction for modulating the electronic structure of g-C3N4 photocatalysts. Fu et al.38 presented a single-atom Fe-doped [email protected]3N4 joint electronic system, exhibiting 18.3 times higher HER of BCN. We previously reported a atomically dispersed Cu1-N3 embedded g-C3N4, generating an outstanding photocatalyst for hydrogen evolution with 35.4 times higher HER than BCN.39 Subsequently, Xiao et al.40 reported Cu single atom-incorporated g-C3N4 tubes, showing a 30 times higher HER than BCN. However, regarding the future applications of g-C3N4 in solar H2 production, further improvements in photocatalytic efficiency still remain a challenge. Like Cu, Ag belongs to the IB group, which has a similar configuration of extra-nuclear electrons (4d105s1) to Cu (3d104s1). However, the Ag atom has a distinct atomic radius and proton number from Cu, where a new horizon may emerge by embedding single Ag atoms into g-C3N4 framework via strong Ag-N bonding for the modulation of its electronic structure. To the best of our knowledge, no reports regarding this issue can be found. Herein, we, for the first time, have prepared a single-atom Ag implanted hollow carbon nitride sphere (Ag1N3-HCNS) with Ag1-N3 coordination through a supramolecular assembly of melamine and melamine-Ag complex (Mel-Ag) with cyanuric acid followed by a pyrolysis process in N2 atmosphere. The atomically dispersed Ag1-N3 moieties embedded within nanosheets of g-C3N4 via Ag-N bonding were unambiguously confirmed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray absorption near-edge structure (XANES), and X-ray photoelectron spectroscopy (XPS) with/without Ar plasma etching. The combination of experimental results and density functional theory (DFT) calculations clearly demonstrate that the implantation of single-atom Ag within the g-C3N4 framework remarkably promotes visible light absorption and notably improves the separation efficiency of charge carriers, resulting from the highly efficient modulation of electronic structure of g-C3N4 via strong covalent Ag-N bonding. Asa result, Ag1N3-HCNS shows an unprecedentedly high visible-light photocatalytic HER of 17.95 mmol g−1 h−1 under an atmospheric pressure, and a remarkable apparent quantum yield (AQY) of 23.6% at 420 nm. The achieved HER over Ag1N3-HCNS is 193 times higher than that on BCN, notably outperforming the previously reported g-C3N4 photocatalysts so far in the literature. This work opens a new window for improving the photocatalytic efficiency, a bottleneck issue, of g-C3N4 photocatalysts via efficient electronic structure modulation of tri-s-triazine frameworks. Experimental Methods Synthesis of pristine HCNS According to references,39,42 0.5 g melamine was dissolved in dimethyl sulfoxide (DMSO) to obtain solution A, and 0.51 g cyanuric acid was dissolved in DMSO to obtain solution B. Then, the resulting solution B was added into the above solution A under vigorous stirring for 10 min to form the precursor of HCNS. After filtration and washing, the resulting precipitate was dried at 60 °C for 12 h and then calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain the final HCNS. Synthesis of HCNS embedded with single Ag atoms in nanosheets (Ag1N3-HCNS) In detail, the complex melamine-Ag (denoted as Mel-Ag) was presynthesized. After that, 4.3 mg Mel-Ag complex and 0.5 g melamine were dissolved together to obtain solution C, and cyanuric acid was dissolved in DMSO to obtain solution B. Then, solution B was added to solution C under stirring to form the precursor of Ag1N3-HCNS. After filtering and washing, the resulting precipitate was then dried at 60 °C for 12 h and calcined at 550 °C for 4 h under nitrogen atmosphere to obtain the final Ag1N3-HCNS catalyst. Synthesis of HCNS embedded with single Cu atoms in nanosheets (Cu1N3-HCNS) According to references,39,42 45.6 mg Cu(NO3)2·3H2O and 0.5 g melamine were dissolved in DMSO to obtain solution D, and 0.51 g cyanuric acid was dissolved in DMSO to obtain solution B. Then, solution B was added into the solution D under vigorous stirring for 10 min to form the precursor of Cu1N3-HCNS. After filtration and washing, the precipitate was dried at 60 °C for 12 h and then calcined at 550 °C for 4 h under nitrogen to obtain the final Cu1N3-HCNS sample. Synthesis of HCNS embedded with Ag nanoparticles in nanosheets (AgNP-HCNS) 0.5 g melamine and NaBH4 were dissolved in 20 mL DMSO to obtain solution E. 15.8 mg AgNO3 and 0.51 g cyanuric acid were dissolved in 10 mL DMSO to obtain solution F. Then, the obtained solution F was added into solution E under magnetic stirring. The precipitate was kept with magnetic stirring for 10 min. After filtration and washing, the precipitate was dried at 60 °C for 12 h and then calcined at 550 °C for 4 h under nitrogen atmosphere to obtain AgNP-HCNS. Synthesis of BCN BCN was prepared on the basis of reference,39 where 1 g melamine was calcined at 550 °C for 4 h under nitrogen to obtain BCN. Characterizations of materials The morphologies of the samples were characterized using a JEOL JSM-5600LV (JEOL, Akishima Shi, Japan) emission scanning electron microscopy (SEM). HAADF-STEM and transmission electron microscopy (TEM) characterization were conducted on a JEOL-2100F (JEOL, Akishima Shi, Japan) field-emission transmission electron microscope (FETEM) with an acceleration voltage of 80 kV. XPS was acquired using an ESCALAB 250 XPS (Thermo Scientific, Waltham, MA, USA) system under the Al Kα X-ray source. Elemental analysis of N and C was collected using an elemental analyzer (Vario EL, Elementar, Heraeus, German). Powder X-ray diffraction (XRD) patterns were performed on an X-ray diffractometer (Rigaku Corporation SmartLab 9, Rigaku, Akishima-shi, Tokyo, Japan) using Cu Kα radiation, operating at 40 kV and 40 mA, ranging from 5° to 80° with a scanning speed of 8°/min. N2 adsorption–desorption measurements were performed on a Beishide instrument (Beishide Corp., Beijing, China). The surface area was calculated using the model of 3H-2000PSI system (Beishide Corp., Beijing, China), and sample pore sizes were obtained from the adsorption data using the t-Plot method. UV–vis diffuse reflectance spectra (DRS) were recorded on a JASCO V-550 UV–vis spectrometer (JASCO, Hachioji-shi, Tokyo, Japan). Photoluminescence (PL) spectra were recorded on a Hitachi F-7000 fluorescence spectrometer (Hitachi, chiyoda-ku, Tokyo, Japan; exciting samples by 376 nm photons). Time-resolved PL measurement was performed on FLS-920 transient steady-state fluorescence spectrometer (Edinburgh Instruments, Livingston, Edinburgh, UK). The amounts of Ag or Cu in the samples were analyzed by an inductively coupled plasma atomic emission spectrometer (ICP-AES) on an Optima 7300 DV (PerkinElmer, Waltham, MA, USA). X-ray absorption fine structure (XAFS) spectra at the Cu K (E0 = 8979 eV) edge and Ag K edge (E0 = 25514 eV) were measured at the BL14W1 beam line of Shanghai Synchrotron Radiation Facility (SSRF). The storage ring of SSRF was working at an energy of 3.5 GeV under "top-up" mode with a constant current of 260 mA. The XAFS data were monochromatized with a Si (111) monochromator and Lytle-type ion chamber. The energy was calibrated according to the absorption edge of pure copper foil. The extended XAFS (EXAFS) data were processed using the Athena and Artemis codes. For the part of XANES spectrum, the change in experimental absorption coefficient with energy μ (E) was processed through background subtraction and normalization procedures and reported as "normalized absorption." For the normalized XANES profiles, the oxidation states of copper and silver were determined by a linear combination fit with a large number of references (Cu2O for Cu+, CuO for Cu2+, and AgNO3 for Ag+). For the EXAFS portion, the Fourier transformed (FT) data in R space were analyzed by applying a C3N4-like model by replacing the Cu/Ag center for Cu-N/Cu-C or Ag-N/Ag-C and first-shell approximate model for Cu-O/Ag-O contributions, respectively. The parameters describing the electronic properties (e.g., correction to the photoelectron energy origin, E0) and local structure environment including coordination number (CN), bond distance (R), and Debye–Waller factor around the absorbing atoms were allowed to vary during the fit process. The fitted ranges for k and R spaces were selected to be k = 3–11 Å−1 with R = 0.8–3.0 Å (k3 weighted). DFT calculations DFT calculations were performed using the Vienna Ab initio Simulation Package (VASP) with ion cores represented by the projector augmented wave (PAW) potentials implemented by VASP. The exchange-correlation interactions were described with the generalized-gradient approximation (GGA) approach and the spin polarized Perdew–Burke–Ernzerhof (PBE) functional. The plane wave basis was set with a cut off energy of 400 eV for all calculations. Geometries of the catalyst models were fully relaxed using a damped molecular dynamics method until the forces on all atoms were less than 0.03 eV Å−1. The lattice constants of the Ag1N3-HCNS and Cu1N3-HCNS models were calculated to be a = b = 14.32 Å and c = 20.00 Å. The k-space integration was sampled using a 3*3*1 Monkhorst–Pack grid. A 20 Å vacuum layer in the z direction was built to avoid interactions between repeating slabs. For the orbital distributions of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the value of iso-surface was set to 0.015 e Å−3. Photoelectrochemical measurements Photoelectrochemical measurements were performed on a CHI660E electrochemical workstation using a conventional three-electrode cell. The working electrodes were each fabricated by coating an indium-doped tin oxide (ITO) glass with an as-prepared catalyst. Experimental conditions for the photocurrent test: 0.5 M Na2SO4 aqueous solution was used as the electrolyte (pH 7.1, 25 °C); Ag/AgCl electrode was used as the reference electrode, and Pt plate was used as the counter-electrode. Experimental conditions for the Mott–Schottky plots were the same as the aforementioned process. The Ag/AgCl electrode system can be converted to a reversible hydrogen electrode (RHE) system by the following equation: V RHE = V Ag/AgCl + V Ag/AgClVSNHE 0 + 0.059 pH (1)where V Ag / AgClVSNHE 0 is 0.1976 V at 25 °C. Photocatalytic performance tests All photocatalytic hydrogen evolution experiments were carried out in a top-illuminated vessel in N2 atmosphere (at atmosphere pressure condition) by visible light irradiation. In detail, 10 mg photocatalyst was dispersed in 100 mL triethanolamine (TEOA) aqueous solution (10 mL TEOA/90 mL water). Pt (3 wt %) was loaded on the photocatalysts as a cocatalyst by a general photodeposition method. The reaction solution was evacuated several times to completely remove air, and then was re-filled with N2 to maintain an atmospheric pressure condition. The reactor was irradiated by a 300 W Xe lamp equipped with a 420 nm cut-off filter (PLSSXE300/300UV, Perfectlight, Beijing, China). The temperature of the reactant solution was maintained at 15 °C of constant temperature by a flow of cooling water during the whole reaction test process. The resulting hydrogen product was analyzed by a GC-9790 gas chromatograph with a thermal conductive detector. Wavelength-dependent AQY of H2 evolution was obtained under different wavelengths of light (400, 420, 450, and 520 nm). The AQY were calculated by the following equation: AQY ( % ) = 2 × Amount of H 2 molecules evolved Number of incident photons × 100 (2) Results and Discussion Structural characterization of as-prepared materials In this work, a single-atom Ag implanted HCNS (Ag1N3-HCNS) was prepared by the supramolecular assembly process of melamine and Mel-Ag with cyanuric acid followed by a pyrolysis process in N2 (Figure 1a). According to our previous reports,39,42 the single-atom Cu1-N3 species embedded HCNS (Cu1N3-HCNS), pristine HCNS, and AgNP-HCNS were prepared for comparison. The intercalation-structured HCNSs composed of carbon nitride nanosheets were observed on SEM (Figures 1b–1d and Supporting Information Figure S1a) and TEM (Figures 1e–1g) images. The corresponding elemental mappings verify that the Ag and Cu atoms were homogeneously distributed in the entire carbon nitride nanosheets ( Supporting Information Figures S2 and S3), and the Ag and Cu contents of Ag1N3-HCNS and Cu1N3-HCNS were and wt as determined by The TEM ( Supporting Information Figures and that no Ag or Cu NPs were on the Ag1N3-HCNS and Ag NPs can be observed on AgNP-HCNS ( Supporting Information Figure The atomically dispersed Ag atoms in Ag1N3-HCNS (Cu1N3-HCNS) are by HAADF-STEM as (Figures and by Supporting Information Figure and no on the properties and N/C the of a low of Ag or Cu atoms within the framework. to the pristine HCNS, Ag1N3-HCNS and Cu1N3-HCNS weak at and (Figure as that the g-C3N4 is not by the of Figure 1 of of SEM of Ag1N3-HCNS Cu1N3-HCNS and pristine HCNS TEM of Ag1N3-HCNS Cu1N3-HCNS and HCNS and HAADF-STEM of Ag1N3-HCNS and Cu1N3-HCNS patterns of HCNS, and AgNP-HCNS. Download figure Download PowerPoint Chemical and coordination characterization XPS analysis more of the samples (Figures and Supporting Information Figure to pristine HCNS, Ag1N3-HCNS and Cu1N3-HCNS a of higher energy of N on N XPS spectra ( Supporting Information Figure the coordination of N with the embedded metal via A new on XPS spectra of Ag1N3-HCNS and Cu1N3-HCNS (Figures can be to bonding and The of N ( Supporting Information is a further indicator of coordination of Ag or Cu with the remarkably of Ag and Cu XPS Ar plasma ( Supporting Information Figure the implantation of Ag and Cu atoms within the carbon nitride nanosheets of Ag1N3-HCNS and Figure 2 N XPS spectra of Ag1N3-HCNS Cu1N3-HCNS and HCNS and Ag XANES spectra of Ag1N3-HCNS and Cu XANES spectra of Cu1N3-HCNS and Fourier spectra from Ag EXAFS of Ag1N3-HCNS and Cu EXAFS of Cu1N3-HCNS and EXAFS of Ag1N3-HCNS and Cu1N3-HCNS in R in Figure of XANES in Figure structure model of Ag1N3-HCNS. in Figure structure model of Cu1N3-HCNS. Download figure Download PowerPoint The electronic structure and local coordination environment of Ag and Cu species are further by X-ray absorption spectroscopy The of XANES for Ag1N3-HCNS is different from that of AgNO3 and Ag (Figure that the for the single Ag atom may be of the electron caused by interactions of single Ag atoms with g-C3N4 via Ag-N bonding. The in Figure shows that the of XANES for Ag1N3-HCNS is quite to Ag the of Ag is The of the single Ag atom was further by XPS in Supporting Information Figure the at and eV can be to Ag and Ag respectively. can be into at and respectively. The at and eV are to the and at and can be to the The results that the single-atom Ag in the Ag1N3-HCNS in the of which is with the results from From the Cu the absorption of Cu1N3-HCNS between CuO and (Figure the oxidation of Cu 1 in Fourier spectra from Ag EXAFS of Ag1N3-HCNS (Figure and Cu EXAFS of Cu1N3-HCNS (Figure no and coordination bond on the that Ag and Cu atoms are atomically dispersed in the HCNS the EXAFS results and DFT calculations the coordination model structures of Ag-N and over HCNS with N atoms one M or atom (Figures and and Supporting Information Photocatalytic H2 evolution The test of photocatalytic H2 evolution reaction performance was performed to the modulating of implantation of atomically dispersed Ag1-N3 moieties within the g-C3N4 by using as a and wt % Pt as under visible light and atmospheric pressure From Figure the developed Ag1N3-HCNS shows an unprecedented high HER of 17.95 mmol g−1 which is 193 times higher than that of BCN mmol g−1 under the same test However, AgNP-HCNS H2 evolution mmol g−1 which is lower than that of BCN. To the for the photocatalytic performance of electron electrochemical spectra and transient photocurrent measurements were From (Figure different from the HCNS and the single-atom Ag or HCNS with a strong at a g value of AgNP-HCNS shows no on the spectrum, that the electronic system of g-C3N4 is during the pyrolysis process of the Ag assembly at 550 °C for 4 no change on the a AgNP-HCNS shows a quite higher charge (Figure and a charge photocurrent (Figure than the g-C3N4 photocatalysts. The separation and of charge of AgNP-HCNS to its photocatalytic for hydrogen Ag1N3-HCNS and Cu1N3-HCNS and times higher HER than pristine HCNS. It the of implantation of Ag and Cu of IB on g-C3N4 regarding photocatalytic H2 and Ag is far to Cu for the photocatalysis of g-C3N4. the silver is from to wt the HER still remains as high as mmol g−1 h−1 ( Supporting Information Figure To the best of our knowledge, such excellent photocatalytic hydrogen evolution performance is far to the most reported photocatalysts under atmospheric pressure conditions ( Supporting Information To the photocatalytic performance of the developed catalyst with that reported in literature, the BCN mmol g−1 h−1 HER can be used as a and a factor can be The of the HER rate on the g-C3N4 to that on the BCN under the same test conditions presents an indicator for the of the developed new which can be as From Supporting Information the developed Ag1N3-HCNS catalyst shows a of 193 times higher HER rate than BCN under the same reaction remarkably outperforming the reported g-C3N4 in the literature. To the implanted single-atom as an active or not for photocatalytic hydrogen production, as a to modulate electronic structure of g-C3N4, the photocatalytic performance test of the as-prepared photocatalysts was performed Pt Supporting Information Figure shows that the Ag1N3-HCNS and Cu1N3-HCNS a low HER of and 0.015 mmol g−1 of are to HCNS, and BCN. It presents that the embedded single-atom Ag or Cu not as active sites for H2 and the Pt as an active is for the outstanding photocatalytic performance of Ag1N3-HCNS mmol g−1 The embedded single-atom Ag or Cu into the of g-C3N4 improves the photocatalytic performance of HCNS by the modulation of electronic structure than as active which is different from the previously reported results that the SAM as an active In the AQY of Ag1N3-HCNS is calculated to be 23.6% at a light of 420 nm (Figure the photocatalytic of A

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