Coordination Polymer Derived NiS@ g-C3N4 Composite

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Coordination polymer derived NiS@g-C3N4 composite photocatalyst for sulfur vacancy and photothermal effect synergistic enhanced H2 production Lele Lu, Xinxin Xu, Kaili An, Yun Wang, and Fa-Nian Shi ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/acssuschemeng.8b02153 • Publication Date (Web): 19 Jul 2018 Downloaded from http://pubs.acs.org on July 22, 2018

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ACS Sustainable Chemistry & Engineering

Coordination

polymer

derived

NiS@g-C3N4

composite

photocatalyst for sulfur vacancy and photothermal effect synergistic enhanced H2 production Lele Lu,a Xinxin Xu*,a Kaili An,a Yun Wang*,a Fa-nian Shi*b a

Department of Chemistry, College of Science, Northeastern University, Shenyang

110819, China b

School of Science, Shenyang University of Technology, Shenyang 110870, China

KEYWORDS: Coordination polymer; NiS@g-C3N4 photocatalyst; sulfur vacancy; photothermal effect; H2 production

*Author to whom correspondence should be addressed. Tel: +86-024-83684533, Fax: +86-024-83684533. * E-mail: [email protected] (Prof. X. X. Xu); [email protected] (Prof. Y. Wang); [email protected] (Prof. F. N. Shi).

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ABSTRACT To obtain the photocatalyst composed by sulfur vacancies rich NiS and graphitic carbon nitride (g-C3N4), a simple method is found out using coordination polymer as precursor. Base on this strategy, an effective composite photocatalyst, NiS@g-C3N4, is synthesized successfully through the calcination of a Ni2+ based coordination polymer with 2-Mercapto-5-propylpyrimidine as ligand. In this photocatalyst, the NiS nanoparticles with small size disperse evenly in 2-Mercapto-5-propylpyrimidine derived g-C3N4. Electron paramagnetic resonance (EPR) suggests there are a lot of sulfur vacancies in NiS@g-C3N4. NiS@g-C3N4 exhibits intensive adsorption in near-infrared region, which endows NiS@g-C3N4 promising photothermal effect. With a 980 nm laser as light source (0.44 W·cm-2), the aqueous dispersion of NiS@g-C3N4 exhibits a temperature elevation of 56.7 ˚C with photothermal conversion efficiency of 58.2%. Under irradiation of simulated solar light, without Pt co-catalyst, NiS@g-C3N4 possesses promising photocatalytic H2 production rate, with the value 31.3 mmol·g-1·h-1. In 5 cycles of reactions for 30 h, the H2 production rate keeps constant. The synergy between sulfur vacancy and photothermal effect of NiS play significant roles in the enhancement of H2 production property.


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INTRODUCTION Nowadays, the serious environmental issues and energy shortage caused by rapid depletion of oil, coal and natural gas has attracted more and more endeavor devoted to exploiting clean and renewable energy sources.1-3 For its high enthalpy value and benign combustion product (H2O), hydrogen is considered as a perspective clean energy to replace above traditional fossil fuels.4-6 To obtain hydrogen energy, photocatalytic water splitting is an economical and eco-friendly method. Recently studies suggest graphitic carbon nitride (g-C3N4) is an excellent photocatalyst, because of its band gap and structure, g-C3N4 is visible light active for H2 production.7-11 In H2 production, the composite photocatalyst built from NiS and g-C3N4 possesses obvious advantage over neat g-C3N4, because NiS can act as a co-catalyst, which impedes recombination of electrons and holes and improves H2 generation. 12-15 Furthermore, the strong near-infrared (NIR) adsorption of NiS can extent photo-response region effectively.16 More importantly, NiS also has obvious advantage in price than noble metal co-catalyst, such as Pt. To date, some composite photocatalysts composed by g-C3N4 and NiS have been synthesized, but their H2 production rates are not very satisfied.17,18 This suffers from overgrowth, aggregation and random distribution of NiS, caused by its disorderly self-assemble and precipitation on g-C3N4 during formation process. These can decrease the separation of electrons and holes, which results in deadly influence on H2 production rate. To obtain NiS@g-C3N4 composite photocatalyst with small NiS nanoparticle distributing evenly in g-C3N4, Ni2+ coordination polymer with appropriate thiol group containing N-heterocycle molecule as ligand is an ideal choice, because Ni2+ based coordination polymer can converts to NiS@g-C3N4 directly through calcination. More importantly, in NiS@g-C3N4 production, the calcination of coordination polymer also



possesses some unique merits over other methods.19,20 In the first place, Ni2+ and thiol group containing N-heterocycle molecule are connected with high order in coordination polymer and this is benefit for homogenously distribution of NiS in composite material. Furthermore, the growth of NiS nanoparticle is limited by neighboring thiol group containing N-heterocycle molecule during calcination and this is benefit for the production of NiS nanoparticle in small size. More importantly, in this process, N atoms from thiol group containing N-heterocycle molecule can replace S2- in NiS and occupied its sites. This can generate sulfur vacancies. In photocatalytic H2 production, the existence of vacancy not only improves the separation of electron-hole pairs, but also enhances the light adsorption of a photocatalyst in NIR region.21-29 Based on these facts we anticipate sulfur vacancies rich NiS@g-C3N4 can be obtained from appropriate Ni2+ based coordination polymer precursor.

Scheme 1 Synthesis process of NiS@g-C3N4 composite material with NCP as precursor Our imagination is confirmed to be realizable by a coordination polymer [Ni(MPPI)2]n (named as CP) (MPPI = 2-Mercapto-5-propylpyrimidine). With nanoparticle of this coordination polymer (NCP) as precursor, a g-C3N4 based composite photocatalyst, NiS@g-C3N4, was synthesized successfully with NiS as co-catalyst. In this composite photocatalyst, small NiS nanoparticles (6 to 8 nm) distribute homogenously in g-C3N4. Electron paramagnetic resonance (EPR) reveals


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sulfur vacancies exist in NiS@g-C3N4 composite photocatalyst. NiS@g-C3N4 exhibits intensive near-infrared light adsorption, which donates it promising photothermal effect. With a 980 nm laser, its aqueous dispersion exhibits a temperature increasing of 56.7 ˚C at power density 0.44 W·cm-2, with photothermal conversion efficiency of 58.2%. NiS@g-C3N4 exhibits very excellent H2 production activity. Without Pt co-catalyst, its H2 generation rate achieves 31.3 mmol·g-1·h-1, which keeps stable after 5 successive cycles of reactions. Under near-infrared light irradiation, NiS@g-C3N4 also shows tempting photocatalytic H2 production activity. Mechanism study illustrates, the outstanding H2 production property originates from synergy of sulfur vacancy and photothermal effect.

Figure 1 (a) 3D structure of CP composed by supramolecular interactions; (b) SEM image of NCP RESULTS AND DISCUSSION Structural study In the structure of CP, there exists one independent Ni2+. Ni2+ links with three N atoms of three different MPPI molecules. The Ni-N bond distances are in the range of 2.012 to 2.126 Å. sulfur atom occupies the final coordination site of Ni2+. The Ni-S bond distance is 2.353 Å. With MPPI as bridging ligands, neighboring Ni2+ ions are connected together and form the one-dimensional chain. If the π-π interactions between MPPI ligands are concerned, these chains are further linked and generates



three-dimensional supramolecular network (Figure 1a). The nanoparticle of this coordination polymer (NCP) is synthesized in microwave hydrothermal condition. TEM suggests the size of NCP is about 40 to 60 nm (Figure 1b). It exhibits spherical appearance.

Figure 2 (a) PXRD of NiS@g-C3N4; (b) FTIR spectra of NiS@g-C3N4; (c) Solid-state 13C NMR spectra of NiS@g-C3N4; (d) EPR of NiS@g-C3N4

Figure 3 TEM image of (a) NiS@g-C3N4(A); (b) NiS@g-C3N4(B), (c) NiS@g-C3N4(C); (d) HRTEM image of NiS@g-C3N4(A) For NCP, the products obtained after calcination at 500, 550 and 600 ˚C were


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named as NiS@g-C3N4(A), NiS@g-C3N4(B) and NiS@g-C3N4(C), respectively. Their structures were analyzed with PXRD (Figure 2a). All these samples exhibit intensive peaks at 30.2˚, 34.7˚, 45.0˚ and 53.5˚. These diffraction peaks are in agreement with (100), (101), (102) and (110) planes of NiS (JCPDS NO. 02-1280). This is almost similar with the results of elemental analysis. Based on elemental analysis, from NiS@g-C3N4(A) to NiS@g-C3N4(C), the contents of Ni and S are 4.6, 4.4 %; 4.5, 4.2 % and 4.1, 3.9 %. In these samples, the diffractions from g-C3N4 vanish completely. To confirm the existence of g-C3N4, FTIR is an ideal method (Figure 2b). In FTIR spectra, the peaks emerging at 1618, 1406, 1321 and 1236 cm-1 originates from the characteristic bands of CN heterocycle. The remained peak at 805 cm-1 can be ascribed to s-triazine ring. FTIR suggest 2-Mercapto-5-propylpyrimidine has been converted to g-C3N4 successfully. Solid-state supports this conclusion. In

13

13

C NMR spectrum also

C NMR spectrum, two signals emerge at 156.1 and

163.9 ppm, which are characteristic peaks belonging to carbon atoms in -CN3 and CN2(NH2). Their appearance confirms poly(tri-s-triazine) fragment has been formed, which is the fundamental unit in g-C3N4 (Figure 2c). As revealed by elemental analyses, in NiS@g-C3N4 composite materials, the C/N ratio ranges from 0.749 to 0.750. The results are very close he theoretical value g-C3N4 (Table 1). In these NiS@g-C3N4 composite photocatalysts, to prove the existence of sulfur vacancies, EPR was applied. All the composite photocatalysts possess a resonance signal at g = 2.005. Based on recent research, this signal is the symbol of sulfur vacancy.30,31 This signal decays obviously from NiS@g-C3N4(A) to NiS@g-C3N4(C). This result illustrates NiS@g-C3N4(A) possesses more sulfur vacancy than NiS@g-C3N4(B) and NiS@g-C3N4(C). In general, the existence of sulfur vacancy can prompt the electron movement. This facilitates the separation of electron-hole pairs. This prompts the



improvement of H2 production rate. So, we expect NiS@g-C3N4(A) possesses the highest hydrogen production rate.

Figure 4 XPS survey of (a) NiS@g-C3N4(A); (b) NiS@g-C3N4(B); (c) NiS@g-C3N4(C); C1s spectra of (d) NiS@g-C3N4(A); (e) NiS@g-C3N4(B); (f) NiS@g-C3N4(C); N1s spectra of (g) NiS@g-C3N4(A); (h) NiS@g-C3N4(B); (i) NiS@g-C3N4(C) TEM was employed to study the morphology of NiS@g-C3N4 composite photocatalysts. From NiS@g-C3N4(A) to NiS@g-C3N4(C), they all exhibit similar appearance with NCP, besides some small particles distribute homogenously in its framework (Figure 3a to 3c). The dimension of these small particles ranges from 6 to 8 nm. More concrete structural information of NiS@g-C3N4 composite photocatalyst can be obtained from high resolution TEM. Here, NiS@g-C3N4(A) was chosen as an example (Figure 3d). In NiS@g-C3N4(A), the lattice spacing with distance 0.296 nm originates from (100) plane of NiS.32 Except the lattice spacing from NiS, another type of lattice fringe is also observed in NiS@g-C3N4(A), with the spacing about 0.326 nm. This can be ascribed to (002) plane from g-C3N4.33-35 The distinctive


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structural feature of NiS@g-C3N4 originates from two respects. At first, the dimension of NiS nanoparticle is limited in great extent during calcination process, because its growth is restrict by neighboring 2-Mercapto-5-propylpyrimidine molecules. Secondly, Ni2+ and 2-Mercapto-5-propylpyrimidine arrange neatly, which result in evenly distribution of NiS in the composite material. Table 1 The element contents of NiS@g-C3N4 composite photocatalysts. NiS@g-C3N4 Ni (%) S (%) C (%) N (%)

A 4.3 4.2 39.2 52.3

B 4.4 4.3 39.1 52.2

C 4.2 4.1 39.3 52.4

To investigate the compositions and elemental states of a photocatalyst, XPS is an effective method. For NiS@g-C3N4 composite photocatalyst, its XPS survey spectrum shows peaks at 163.9, 284.9, 400.2 and 856.6 eV (Figure 4a to 4c). These peaks are S 2p, C 1s, N 1s and Ni 2p respectively. High-resolution Ni 2p spectra illustrate Ni 2p3/2 and Ni 2p1/2 peaks at 854.1 and 870.2 eV, which confirms the nickel element exists in Ni2+ form (Figure S1).36,37 High-resolution spectra of S 2p is parted to two peaks at about 161 and 162 eV, which are in well consistence with S 2p3/2 and S 2p1/2 of S2(Figure S2).38,39 Furthermore, from NiS@g-C3N4(A) to NiS@g-C3N4(C), the S 2p

3/2

peak moves to higher binding energy region slightly, this can be attributed to the reduction of sulfur vacancy concentration.40 These results further illustrate NiS has been formed successfully through the calcination of Ni2+ based coordination polymer. The existence of carbon element is studied with high-resolution C 1s spectra. After resolution, two peaks appear at 284.6 and 288.2 eV. The first signal can be ascribed to C-C bonds, which originates from impurities with graphitic form in g-C3N4. The second signal at 288.2 eV corresponds to the carbon with sp2 hybrid mode in N-C=N



fragment, which is a remarkable character in g-C3N4 (Figure 4d to 4f).41,42 The content ratios between C-C and N-C=N range from 0.736 to 0.752, and this further confirm after calcination MPPI converts to g-C3N4 (Table S1). As revealed by high resolution N 1s spectra, there are three kinds of different N species in NiS@g-C3N4 (Figure 4g to 4i). The peak at 397.9 eV can be ascribed to the nitrogen atom in C=N-C, which connects with one carbon atom through C-N single bond and links with another carbon atom by C=N double bond.43,44 The signal emerging at 399.5 eV originates from tertiary N species (N-(C)3).45,46 The appearance of these two signals confirms g-C3N4 has formed after calcinations. In high resolution N 1s spectra, the last signal locates at 396.3 eV. This peak originates from coordinated nitrogen atoms in Ni-N bonds.47 Its emergence suggests some N atoms dope in NiS and occupy the positions of S2-, which can generate sulfur vacancy in the composite material. The results of EPR and XPS both confirm sulfur vacancies have been formed in NiS@g-C3N4 composite material. From NiS@g-C3N4(A) to NiS@g-C3N4(C), the content of Ni-N decreases gradually, which also illustrates the concentration of sulfur vacancy reduces (Table S2). For NiS@g-C3N4 composite materials, their pore characters can be obtained from N2 adsorption/desorption isotherms. The hysteresis loop ranging from 0.4 to 1.0 is distinctive, which illustrates mesoporous feature of NiS@g-C3N4 composite materials. For NiS@g-C3N4(A), NiS@g-C3N4(B) and NiS@g-C3N4(C), their specific surface areas are 322.1, 318.9 and 330.2 m2/g respectively (Figure 5a to 5c). The pore size distribution of these composite photocatalysts are obtained from BJH mode, from NiS@g-C3N4(A) to NiS@g-C3N4(C), their average pore size are 5.7, 5.9 and 6.3 nm (Figure 5d). The mesoporous feature and high surface area can enhance the transportation of photogerated electrons, which facilitate the improvement of


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photocatalytic H2 production rate.

Figure 5 N2 sorption isotherms of (a) NiS@g-C3N4(A); (b) NiS@g-C3N4(B); (c) NiS@g-C3N4(C); (d) BJH pore distribution of NiS@g-C3N4

Figure 6 (a) DRS of NiS@g-C3N4; (b) PL spectra of NiS@g-C3N4; (c) Photocurrent spectra of NiS@g-C3N4; (d) EIS of NiS@g-C3N4 Optical and electrochemical analysis Compared with ultraviolet and visible light active g-C3N4 photocatalyst, NiS@g-C3N4 shows intensive absorption in both visible light and near infrared (NIR)



region as illustrated by diffuse reflectance spectra (DRS) (Figure 6a). In DRS, the region below 550 nm can be associated to g-C3N4. The extension of light adsorption scope from visible light region to near infrared region facilitates the usage of NiS@g-C3N4 composite photocatalyst in practical conditions. Based on DRS, we can also find NiS@g-C3N4(A) shows more intensive adsorption than NiS@g-C3N4(B) and NiS@g-C3N4(C) in NIR region. Photoluminescence (PL) spectrum is an effective method to judge the separation efficiency in electrons and holes. Here, for NiS@g-C3N4, after excited at 425 nm, the main emissions emerge at 482 nm (Figure 6b). To our knowledge, for a photocatalyst, intensive PL emission reflects low photogenerated electrons and holes separation rate, while weak emission intensity represent high electron-hole pair separation efficiency. Here, from NiS@g-C3N4(A) to NiS@g-C3N4(C), the PL emission intensity decays gradually, which suggests, in NiS@g-C3N4(A), electrons-hole pairs can be separated effectively than the other two photocatalysts. To confirm the results of PL spectrum, electrochemical methods are used.

Figure 7 (a) The H2 production curve of NiS@g-C3N4; (b) H2 production rate of NiS@g-C3N4; (c) The mechanism of photocatalytic process; (d) The interaction between H2O and NiS@g-C3N4 as well as the generation process of H2; (e) Contact angles (CA) of NiS@g-C3N4; (f) Temperature change of aqueous solution of NiS@g-C3N4 as a function of time;


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For NiS@g-C3N4 composite photocatalysts, the photocurrent spectrum is an effective tool to study the separation situation of electrons and holes. When irradiated by simulated solar light, photocurrent appears immediately. As the light source is turn off, the photocurrent vanishes at once (Figure 6c). In these composite photocatalysts, NiS@g-C3N4(A) shows the most intensive photocurrent. This suggests in NiS@g-C3N4(A) composite photocatalyst, the electrons and holes are parted more quickly than NiS@g-C3N4(B) and NiS@g-C3N4(C). The charge transportation process in photocatalysis can be discussed concretely with EIS (Figure 6d). Compared with NiS@g-C3N4(B) and NiS@g-C3N4(C), NiS@g-C3N4(A) possesses a smaller arc radius. This suggests the electrons on interfaces of NiS@g-C3N4(A) can be transported away quickly, which restricts the combination of photogenerated electrons and holes. So, we can anticipate that NiS@g-C3N4(A) possesses the most promising photocatalytic activity in these three composite photocatalysts.

Figure 8 (a) Recycled photocatalytic H2 production for NiS@g-C3N4(A); (b) PXRD of NiS@g-C3N4(A) before and after H2 production Photocatalytic H2 production and mechanism study For NiS@g-C3N4 composite material, its H2 production activity was measured under simulated solar light irradiation. From NiS@g-C3N4(A) to NiS@g-C3N4(C), their H2 production rate achieves at 31.3, 12.2 and 3.7 mmol·h-1·g-1 (Figure7a, 7b). These values are much higher than single NiS and g-C3N4 with H2 production rate 0.33 and 1.1 mmol·h-1·g-1, which illustrates the combination of NiS and g-C3N4 can



improve the photocatalytic activity greatly (Figure S3). Furthermore, these results also suggest the H2 production rate is influenced seriously by calcination temperature. With increasing of temperature, H2 generation rate of NiS@g-C3N4 composite material decreases obviously. The mechanism in photocatalytic H2 production is analyzed to illustrate this phenomenon (Figure 7c). After irradiated by simulated solar light, in NiS@g-C3N4, g-C3N4 is excited, which produces electrons and holes on its conductive band and valence band respectively. For NiS, the energy level of its conductive band is lower than g-C3N4. So, the electrons on CB of g-C3N4 move to NiS. This prompts the separation of electron-hole pairs. The reduction of H2O is accomplished as follows: at first, water molecules attached on NiS surface were reduced by electrons and produce H atoms; then two H atoms combine together and form H2 through a Tafel process (Figure 7d). In this reaction, besides serving as electron carrier, NiS also acts as water molecule trapper because its positive charged sulfur vacancy can capture high negativity oxygen atom of water molecule and fasten it on surface, which facilitates the reduction of water molecule and prompts H2 production. Compared with the other two analogues, NiS@g-C3N4(A) possesses higher sulfur vacancy concentration. At first, this prompts the separation of electron-hole pairs. Furthermore, as revealed by contact angles, the increasing of sulfur vacancy improves the hydrophilicity of NiS@g-C3N4, which improves the adsorption of water molecule on its surface (Figure 7e). All these factors boost the reduction of H2O as well as the generation of H2. As an excellent photothermal agent with intensive NIR absorption, NiS can convert absorbed photo energy to thermal energy effectively.48 So, for water splitting H2 production, an endothermic reaction, the contribution of photothermal effect on H2 production cannot be ignored. Here, the photothermal conversion efficiency of


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NiS@g-C3N4 was measured with modified method of Roper.49,50 The temperature elevation of NiS@g-C3N4 aqueous solution was recorded as a function of irradiated time with 980 nm laser, until a steady state temperature was reached (Figure 7f). In 1000 s, the temperature of NiS@g-C3N4(A) increases from 25.5 to 82.2 ˚C with photothermal conversion efficiency achieves as high as 58.2 %. This value is much higher than some previously reported photothermal agents, such Cu9S5 and Cu2-xSe. For NiS@g-C3N4(B) and NiS@g-C3N4(C), the temperature elevations are 41.7 and 28.5 ˚C with photothermal conversion efficiency 38.2 and 20.5 % respectively. Compared with the other two analogues, the excellent photothermal conversion efficiency of NiS@g-C3N4(A) originates from high sulfur vacancy concentration, which is benefit for the introduction of free electrons into the crystal lattice of NiS and lead to intensive adsorption in NIR region. Compared with other composite photocatalysts based on g-C3N4, NiS@g-C3N4(A) shows much higher H2 generation property (Table 2).51-63 The excellent photocatalytic activity originates from synergism of sulfur vacancy and photothermal effect. For NiS@g-C3N4(A), in its practical application, the stability is very significant. To study stability of NiS@g-C3N4(A), here, its H2 generation experiments is recycled for five times. After 30 h, the H2 production rate of NiS@g-C3N4(A) still retains at high level (Figure 8a). To study the structure of recycled NiS@g-C3N4(A) composite photocatalyst, PXRD was employed. The result suggests before and after durability experiment, PXRD pattern of NiS@g-C3N4(A) keeps unchanged (Figure 8b). Based on efficiency and stability of NiS@g-C3N4(A), we can conclude it is an ideal photocatalyst for hydrogen generation. CONCLUSIONS In summary, with a new method employing Ni2+ based coordination polymer as



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precursor, a highly effective NiS@g-C3N4 composite photocatalyst is obtained through calcination. EPR illustrates, there exist a lot of sulfur vacancies in NiS@g-C3N4 composite photocatalyst. Furthermore, NiS@g-C3N4 composite photocatalyst also shows intensive photothermal effect. NiS@g-C3N4 composite photocatalyst possesses much higher H2 production efficiency than other g-C3N4 based photocatalysts. Its H2 production rate arrives at 31.3 mmol·g-1·h-1. The advantages of NiS@g-C3N4 in H2 production activity originate from sulfur vacancy and photothermal effect. For NiS@g-C3N4, its H2 production rate keeps stable after five cycle continuous experiments for 30 h. All above mentioned merits make NiS@g-C3N4 a perspective material in H2 application. Table 2 Comparison of H2 production rate of other g-C3N4 based photocatalyst and NiS@g-C3N4(A) in this work. Photocatalyst

Catalyst dose (g)

NiS/g-C3N4 NiS/g-C3N4 NiS/g-C3N4 NiS,CdS/g-C3N4 NiS,CNTs/g-C3N4 CdLa2S4/g-C3N4 Ni(OH)2/g-C3N4 CdS/g-C3N4 WS2/g-C3N4 Cd0.2Zn0.8S/g-C3N4 CdS,r-GO/g-C3N4 CdS,Ni(OH)2/g-C3N4 MoS2/g-C3N4 MoS2/g-C3N4 Ta2O5/g-C3N4 ZnIn2S4/g-C3N4 NiS@g-C3N4(A)

0.005 0.05 0.1 0.3 0.05 0.05 0.2 0.02 0.05 0.05 0.02 0.001 0.05 0.01 0.1 0.05 0.02

H2 Production (mmol·h-1·g-1) 0.99 0.03 0.5 2.6 0.5 5.98 0.2 0.6 0.1 4.16 20.2 0.11 1.3 0.25 0.037 0.95 31.3

ASSOCIATED CONTENT


Ref. 12 13 14 15 18 33 36 38 43 44 45 52 54 55 57 63 Here

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Supporting Information Experimental details; the contents of different C and N in NiS@g-C3N4; XPS spectra of Ni 2p and S 2p of NiS@g-C3N4; The H2 production curve of NiS and g-C3N4. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by National Natural Science Foundation of China (21303010, 21571132); Fundamental Research Funds for the Central University (N170504025).



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Table of Contents Graphic

A new strategy is explored to fabricate sulfur vacancy and photothermal effect synergistic enhanced NiS@g-C3N4 composite photocatalyst for H2 production.


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Coordination Polymer Derived NiS@ g-C3N4 Composite

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