Synthesis of heterostructure δ-MnO2/h-MoO3 nanocomposite and the enhanced photodegradation activity of methyl orange in aqueous solutions
Source abstract
Abstract
The growing extent of dye pollution by human activities has engendered an urgent need for removing of them through adjustable approaches. The adsorption–photocatalytic technique is attractive and widely employed to address the above issue, since it could achieve pollutant mineralization by the reactive species generated under the light irradiation without other chemicals. In this paper, a series of δ-MnO2/h-MoO3 nanocomposites was successfully synthesized by a simple two-step method. The structure and morphology of the as-prepared nanocomposite have been assessed by XRD, FESEM, TEM, XPS and BET surface area measurements, and the optical properties were detected by the UV–Vis diffuse reflectance, photoluminescence (PL) and photocurrent measurements. Photocatalytic performances of the prepared δ-MnO2/h-MoO3 nanocomposite were evaluated through photodegradation of dyes in solution under simulated sunlight irradiation. After a simple two-step preparation process, the specific surface area (SBET) of the δ-MnO2/h-MoO3 composite was increased by about 4.5 times compared to the pure δ-MnO2 and h-MoO3, and this may result in a great adsorption property for the nanocomposite. With a broader absorption edge, high electron transfer efficiency and lower recombination efficiency of the photogenerated electrons and holes, the photocatalytic activity of the heterostructure δ-MnO2/h-MoO3 composites was improved heavily compared to the single-phase samples. Especially, when 20 mg of δ-MnO2 (0.6 g)/h-MoO3 composite was used to degrade methyl orange (MO) aqueous solution (100 mL, 15 mg L−1), the degradation efficiency could reach 80.55% within 115 min under simulated sunlight irradiation. Additionally, the photodegradation cyclic tests showed that the nanocomposite exhibited excellent stability, as the degradation efficiency reaches 71.02% within 95 min after four cycles, which makes it to have a bright prospect of industrial application. Finally, the reasonable mechanism for the enhanced photocatalytic activity of the heterostructure δ-MnO2/h-MoO3 composites was investigated by active species trapping experiments, and the results showed that the synergistic effect between δ-MnO2 and h-MoO3 as well as the unique flower ball-stick morphology of composites lead to an excellent photocatalytic performance.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Advanced Photocatalysis Techniques · Transition Metal Oxide Nanomaterials · Polyoxometalates: Synthesis and Applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (67)
Show source-provided references
1. Ke J, Duan X, Luo S et al (2017) UV-assisted construction of 3D hierarchical rGO/Bi2MoO6 composites for enhanced photocatalytic water oxidation. Chem Eng J 313:1447–1453. https://doi.org/10.1016/j.cej.2016.11.04810.1016/j.cej.2016.11.048 ↗
2. Gao Z, Xie S, Zhang B, Qiu X, Chen F (2017) Ultrathin Mg-Al layered double hydroxide prepared by ionothermal synthesis in a deep eutectic solvent for highly effective boron removal. Chem Eng J 319:108–118. https://doi.org/10.1016/j.cej.2017.03.00210.1016/j.cej.2017.03.002 ↗
3. Wen Z, Ke J, Xu J et al (2018) One-step facile hydrothermal synthesis of flowerlike Ce/Fe bimetallic oxides for efficient As(V) and Cr(VI) remediation: performance and mechanism. Chem Eng J 343:416–426. https://doi.org/10.1016/j.cej.2018.03.03410.1016/j.cej.2018.03.034 ↗
4. Luo S, Qin F, Ming Y et al (2017) Fabrication uniform hollow Bi2S3 nanospheres via Kirkendall effect for photocatalytic reduction of Cr(VI) in electroplating industry wastewater. J Hazard Mater 340:253–262. https://doi.org/10.1016/j.jhazmat.2017.06.04410.1016/j.jhazmat.2017.06.044 ↗
5. Zhao H, Li G, Tian F, Jia Q, Liu Y, Chen R (2019) g-C3N4 surface-decorated Bi2O2CO3 for improved photocatalytic performance: theoretical calculation and photodegradation of antibiotics in actual water matrix. Chem Eng J 366:468–479. https://doi.org/10.1016/j.cej.2019.02.08810.1016/j.cej.2019.02.088 ↗
6. Tang H, Dai Z, Xie X et al (2019) Promotion of peroxydisulfate activation over Cu0.84Bi2.08O4 for visible light induced photodegradation of ciprofloxacin in water matrix. Chem Eng J 356:472–482. https://doi.org/10.1016/j.cej.2018.09.06610.1016/j.cej.2018.09.066 ↗
7. Gan Y, Wei Y, Xiong J et al (2018) Impact of post-processing modes of precursor on adsorption and photocatalytic capability of mesoporous TiO2 nanocrystallite aggregates towards ciprofloxacin removal. Chem Eng J 349:1–16. https://doi.org/10.1016/j.cej.2018.05.05110.1016/j.cej.2018.05.051 ↗
8. Feng X, Guo H, Patel K et al (2014) High performance, recoverable Fe3O4-ZnO nanoparticles for enhanced photocatalytic degradation of phenol. Chem Eng J 244:327–334. https://doi.org/10.1016/j.cej.2014.01.07510.1016/j.cej.2014.01.075 ↗
9. Wen Z, Lu J, Zhang Y et al (2019) Facile inverse micelle fabrication of magnetic ordered mesoporous iron cerium bimetal oxides with excellent performance for arsenic removal from water. J Hazard Mater 383:121172. https://doi.org/10.1016/j.jhazmat.2019.12117210.1016/j.jhazmat.2019.121172 ↗
10. Wang R, Cheng G, Dai Z et al (2017) Ionic liquid-employed synthesis of Bi2E3 (E = S, Se, and Te) hierarchitectures: the case of Bi2S3 with superior visible-light-driven Cr(VI) photoreduction capacity. Chem Eng J 327:371–386. https://doi.org/10.1016/j.cej.2017.06.11910.1016/j.cej.2017.06.119 ↗
11. Lai C, Zhang M, Li B et al (2019) Fabrication of CuS/BiVO4 (040) binary heterojunction photocatalysts with enhanced photocatalytic activity for Ciprofloxacin degradation and mechanism insight. Chem Eng J 358:891–902. https://doi.org/10.1016/j.cej.2018.10.07210.1016/j.cej.2018.10.072 ↗
12. Chen F, Xie S, Huang X, Qiu X (2017) Ionothermal synthesis of Fe3O4 magnetic nanoparticles as efficient heterogeneous Fenton-like catalysts for degradation of organic pollutants with H2O2. J Hazard Mater 322:152–162. https://doi.org/10.1016/j.jhazmat.2016.02.07310.1016/j.jhazmat.2016.02.073 ↗
13. Singh R, Kumar M, Khajuria H, Sharma S, Sheikh HN (2018) Studies on hydrothermal synthesis of photoluminescent rare earth (Eu3+ and Tb3+) doped NG@FeMoO4 for enhanced visible light photodegradation of methylene blue dye. Solid State Sci 76:38–47. https://doi.org/10.1016/j.solidstatesciences.2017.11.01110.1016/j.solidstatesciences.2017.11.011 ↗
14. Singh R, Kumar M, Khajuria H, Ladol J, Sheikh HN (2018) Hydrothermal synthesis of magnetic Fe3O4–nitrogen-doped graphene hybrid composite and its application as photocatalyst in degradation of methyl orange and methylene blue dyes in presence of copper (II) ions. Chem Pap 72:1181–1192. https://doi.org/10.1007/s11696-018-0385-y10.1007/s11696-018-0385-y ↗
15. Siddiqui SI, Chaudhry SA (2019) Nanohybrid composite Fe2O3-ZrO2/BC for inhibiting the growth of bacteria and adsorptive removal of arsenic and dyes from water. J Clean Prod 223:849–868. https://doi.org/10.1016/j.jclepro.2019.03.16110.1016/j.jclepro.2019.03.161 ↗
16. Zaidi Z, Siddiqui SI, Fatima B, Chaudhry SA (2019) Synthesis of ZnO nanospheres for water treatment through adsorption and photocatalytic degradation: modelling and process optimization. Mater Res Bull 120:110584. https://doi.org/10.1016/j.materresbull.2019.11058410.1016/j.materresbull.2019.110584 ↗
17. Glaze WH, Kang JW, Chapin DH (1987) The chemistry of water treatment processes involving ozone, hydrogen peroxide and ultraviolet radiation. Ozone Sci Eng 9:335–352. https://doi.org/10.1080/0191951870855214810.1080/01919518708552148 ↗
18. Siddiqui SI, Zohra F, Chaudhry SA (2019) Nigella sativa seed based nanohybrid composite-Fe2O3-SnO2/BC: a novel material for enhanced adsorptive removal of methylene blue from water. Environ Res 178:108667. https://doi.org/10.1016/j.envres.2019.10866710.1016/j.envres.2019.108667 ↗
19. Singh R, Kumar M, Khajuria H, Tashi L, Sheikh HN (2018) Nitrogen-doped grapheme-cerium oxide (NG-CeO2) photocatalyst for the photodegradation of methylene blue in waste water. J Chin Chem Soc 66:467–473. https://doi.org/10.1002/jccs.20180031710.1002/jccs.201800317 ↗
20. Singh R, Kumar M, Khajuria H, Ladol J, Sheikh HN (2018) Solvothermal synthesis of ZnO-nitrogen doped graphene composite and its application as catalyst for photodegradation of organic dye methylene blue. Acta Chim Slov 65:319–327. https://doi.org/10.17344/acsi.2017.398810.17344/acsi.2017.3988 ↗
21. Tashi L, Kumar M, Singh R, Khajuria Y, Sheikh HN (2019) Tuning of photoluminescence intensity of europium doped sodium yttrium fluorides synthesized via hydrothermal route. J Mater Sci Mater El 30:14256–14268. https://doi.org/10.1007/s10854-019-01795-y10.1007/s10854-019-01795-y ↗
22. Wen Z, Zhang Y, Wang Y et al (2017) Redox transformation of arsenic by magnetic thin-film MnO2 nanosheet-coated flowerlike Fe3O4 nanocomposites. Chem Eng J 312:39–49. https://doi.org/10.1016/j.cej.2016.11.11210.1016/j.cej.2016.11.112 ↗
23. Zhang L, He Y, Yang X et al (2015) Oxidative carbonylation of phenol to diphenyl carbonate by Pd/MO–MnFe2O4 magnetic catalyst. Chem Eng J 278:129–133. https://doi.org/10.1016/j.cej.2014.11.09610.1016/j.cej.2014.11.096 ↗
24. Siddiqui SI, Chaudhry SA (2018) Nigella sativa plant based nanocomposite-MnFe2O4/BC: an antibacterial material for water purification. J Clean Prod 200:996–1008. https://doi.org/10.1016/j.jclepro.2018.07.30010.1016/j.jclepro.2018.07.300 ↗
25. Kumar M, Singh R, Khajuria H, Sheikh HN (2017) Facile hydrothermal synthesis of nanocomposites of nitrogen doped graphene with metal molybdates (NG-MMoO4) (M = Mn Co, and Ni) for enhanced photodegradation of methylene blue. J Mater Sci Mater El 28:9423–9434. https://doi.org/10.1007/s10854-017-6684-110.1007/s10854-017-6684-1 ↗
26. LeBlanc SE, Fogler HS (1987) The role of conduction valence bands and redox potential in accelerated mineral dissolution. Ozone Sci Eng 9:335–352. https://doi.org/10.1002/aic.69032101310.1002/aic.690321013 ↗
27. Xu X, Zhou X, Li X et al (2014) Electrodeposition synthesis of MnO2/TiO2 nanotube arrays nanocomposites and their visible light photocatalytic activity. Mater Res Bull 59:32–36. https://doi.org/10.1016/j.materresbull.2014.06.02510.1016/j.materresbull.2014.06.025 ↗
28. Pung SY, Chan YL, Sreekantan S, Yeoh F-Y (2016) Photocatalytic activity of ZnO-MnO2 core shell nanocomposite in degradation of RhB dye. Pigm Resin Technol 45:408–418. https://doi.org/10.1108/prt-08-2015-008210.1108/prt-08-2015-0082 ↗
29. Zhou Q, Zhang L, Zuo P et al (2018) Enhanced photocatalytic performance of spherical BiOI/MnO2 composite and mechanism investigation. RSC Adv 8:36161–36166. https://doi.org/10.1039/c8ra06930a10.1039/c8ra06930a ↗
30. Chen Y, Lu C, Xu L et al (2010) Single-crystalline orthorhombic molybdenum oxide nanobelts: synthesis and photocatalytic properties. CrystEngComm 12:3740–3747. https://doi.org/10.1039/c000744g10.1039/c000744g ↗
31. Pan W, Tian R, Jin H et al (2010) Structure, optical, and catalytic properties of novel hexagonal metastable h-MoO3 nano- and microrods synthesized with modified liquid-phase processes. Chem Mater 22:6202–6208. https://doi.org/10.1021/cm102703s10.1021/cm102703s ↗
32. Chithambararaj A, Sanjini NS, Bose AC, Velmathi S (2013) Flower-like hierarchical h-MoO3: new findings of efficient visible light driven nano photocatalyst for methylene blue degradation. Catal Sci Technol 3:1405–1412. https://doi.org/10.1039/c3cy20764a10.1039/c3cy20764a ↗
33. Chithambararaj A, Sanjini NS, Velmathi S, Bose AC (2013) Preparation of h-MoO3 and alpha-MoO3 nanocrystals: comparative study on photocatalytic degradation of methylene blue under visible light irradiation. Phys Chem Chem Phys 15:14761–14769. https://doi.org/10.1039/c3cp51796a10.1039/c3cp51796a ↗
34. Xie Z, Feng Y, Wang F et al (2018) Construction of carbon dots modified MoO3/g-C3N4 Z-scheme photocatalyst with enhanced visible-light photocatalytic activity for the degradation of tetracycline. Appl Catal B Environ 229:96–104. https://doi.org/10.1016/j.apcatb.2018.02.01110.1016/j.apcatb.2018.02.011 ↗
35. Liu H, Lv T, Zhu C, Zhu Z (2016) Direct bandgap narrowing of TiO2/MoO3 heterostructure composites for enhanced solar-driven photocatalytic activity. Sol Energ Mat Sol C 153:1–8. https://doi.org/10.1016/j.solmat.2016.04.01310.1016/j.solmat.2016.04.013 ↗
36. Li W, Chen J, Guo R et al (2017) Facile fabrication of a direct Z-scheme MoO3/Ag2CrO4 composite photocatalyst with improved visible light photocatalytic performance. J Mater Sci Mater El 28:15967–15979. https://doi.org/10.1007/s10854-017-7495-010.1007/s10854-017-7495-0 ↗
37. Anjaneyulu RB, Mohan BS, Naidu GP et al (2018) Visible light enhanced photocatalytic degradation of methylene blue by ternary nanocomposite, MoO3/Fe2O3/rGO. J Asian Ceram Soc 6:183–195. https://doi.org/10.1080/21870764.2018.147901110.1080/21870764.2018.1479011 ↗
38. Xi Q, Liu J, Wu Z et al (2019) In-situ fabrication of MoO3 nanobelts decorated with MoO2 nanoparticles and their enhanced photocatalytic performance. Appl Surf Sci 480:427–437. https://doi.org/10.1016/j.apsusc.2019.03.00910.1016/j.apsusc.2019.03.009 ↗
39. Liu Y, Luo C, Sun J et al (2015) Enhanced adsorption removal of methyl orange from aqueous solution by nanostructured proton-containing δ-MnO2. J Mater Chem A 3:5674–5682. https://doi.org/10.1039/c4ta07112c10.1039/c4ta07112c ↗
40. Shafi PM, Dhanabal R, Chithambararaj A et al (2017) α-MnO2/h-MoO3 Hybrid Material for High Performance Supercapacitor Electrode and Photocatalyst. ACS Sustain Chem Eng 5:4757–4770. https://doi.org/10.1021/acssuschemeng.7b0014310.1021/acssuschemeng.7b00143 ↗
41. Wang Y, Zhang YZ, Dubbink D et al (2018) Inkjet printing of δ-MnO2 nanosheets for flexible solid-state micro-supercapacitor. Nano Energy 49:481–488. https://doi.org/10.1016/j.nanoen.2018.05.00210.1016/j.nanoen.2018.05.002 ↗
42. Chen B, Chen S, Zhao H et al (2019) A versatile beta-cyclodextrin and polyethyleneimine bi-functionalized magnetic nanoadsorbent for simultaneous capture of methyl orange and Pb(II) from complex wastewater. Chemosphere 216:605–616. https://doi.org/10.1016/j.chemosphere.2018.10.15710.1016/j.chemosphere.2018.10.157 ↗
43. Fasfous II, Radwan ES, Dawoud JN (2010) Kinetics, equilibrium and thermodynamics of the sorption of tetrabromobisphenol A on multiwalled carbon nanotubes. Appl Surf Sci 256:7246–7252. https://doi.org/10.1016/j.apsusc.2010.05.05910.1016/j.apsusc.2010.05.059 ↗
44. Wang YS, Tsai DS, Chung WH et al (2012) Power loss and energy density of the asymmetric ultracapacitor loaded with molybdenum doped manganese oxide. Electrochim Acta 68:95–102. https://doi.org/10.1016/j.electacta.2012.02.03810.1016/j.electacta.2012.02.038 ↗
45. Wang S, Li Q, Pu W et al (2016) MoO3–MnO2 intergrown nanoparticle composite prepared by one-step hydrothermal synthesis as anode for lithium ion batteries. J Alloys Compd 663:148–155. https://doi.org/10.1016/j.jallcom.2015.12.04010.1016/j.jallcom.2015.12.040 ↗
46. Liu S, Liu H, Jin G et al (2015) Preparation of a novel flower-like MnO2/BiOI composite with highly enhanced adsorption and photocatalytic activity. RSC Adv 5:45646–45653. https://doi.org/10.1039/c5ra02402a10.1039/c5ra02402a ↗
47. Jittiarporn P, Sikong L, Kooptarnond K et al (2014) Effects of precipitation temperature on the photochromic properties of h-MoO3. Ceram Int 40:13487–13495. https://doi.org/10.1016/j.ceramint.2014.05.07610.1016/j.ceramint.2014.05.076 ↗
48. Han Y, Dong X, Zhang C et al (2012) Hierarchical porous carbon hollow-spheres as a high performance electrical double-layer capacitor material. J Power Sources 211:92–96. https://doi.org/10.1016/j.jpowsour.2012.03.05310.1016/j.jpowsour.2012.03.053 ↗
49. Chithambararaj A, Winston B, Sanjini NS et al (2015) Band gap tuning of h-MoO3 nanocrystals for efficient visible light photocatalytic activity against methylene blue dye. J Nanosci Nanotechnol 15:4913–4919. https://doi.org/10.1166/jnn.2015.984610.1166/jnn.2015.9846 ↗
50. Zou X, Dong Y, Yuan C et al (2019) Zn2SnO4 QDs decorated Bi2WO6 nanoplates for improved visible-light-driven photocatalytic removal of gaseous contaminants. J Taiwan Inst Chem Eng 96:390–399. https://doi.org/10.1016/j.jtice.2018.12.00510.1016/j.jtice.2018.12.005 ↗
51. Li TB, Chen G, Zhou C et al (2011) New photocatalyst BiOCl/BiOI composites with highly enhanced visible light photocatalytic performances. Dalton Trans 40:6751–6758. https://doi.org/10.1039/c1dt10471c10.1039/c1dt10471c ↗
52. Pearson RG (1988) Absolute electronegativity and hardness application to inorganic chemistry. Inorg Chem 27:734–740. https://doi.org/10.1021/ic00277a03010.1021/ic00277a030 ↗
53. Hu Z, Zhou J, Zhang Y, Liu W, Zhou J, Cai W (2018) The formation of a direct Z-scheme Bi2O3/MoO3 composite nanocatalyst with improved photocatalytic activity under visible light. Chem Phys Lett 706:208–214. https://doi.org/10.1016/j.cplett.2018.06.00610.1016/j.cplett.2018.06.006 ↗
54. Wang M, Zhang Y, Jin C, Li Z, Chai T, Zhu T (2019) Fabrication of novel ternary heterojunctions of Pd/g-C3N4/Bi2MoO6 hollow microspheres for enhanced visible-light photocatalytic performance toward organic pollutant degradation. Sep Purif Technol 211:1–9. https://doi.org/10.1016/j.seppur.2018.09.06110.1016/j.seppur.2018.09.061 ↗
55. Skiker R, Zouraibi M, Saidi M, Ziat K (2018) Facile coprecipitation synthesis of novel Bi12TiO20/BiFeO3 heterostructure serie with enhanced photocatalytic activity for removal of methyl orange from water. J Phys Chem Solids 119:265–275. https://doi.org/10.1016/j.jpcs.2018.04.01010.1016/j.jpcs.2018.04.010 ↗
56. Talebi R (2017) New method for preparation Mn2O3–TiO2 nanocomposites and study of their photocatalytic properties. J Mater Sci Mater El 28:8316–8321. https://doi.org/10.1007/s10854-017-6546-x10.1007/s10854-017-6546-x ↗
57. Babu B, Kadam AN, Rao GT, Lee S-W, Byon C, Shim J (2018) Enhancement of visible-light-driven photoresponse of Mn-doped SnO2 quantum dots obtained by rapid and energy efficient synthesis. J Lumin 195:283–289. https://doi.org/10.1016/j.jlumin.2017.11.04010.1016/j.jlumin.2017.11.040 ↗
58. Yamashita H, Ichihashi Y, Zhang SG et al (1997) Photocatalytic decomposition of NO at 275 K on titanium oxide catalysts anchored within zeolite cavities and framework. Appl Surf Sci 121:305–309. https://doi.org/10.1016/S0169-4332(97)00311-510.1016/S0169-4332(97)00311-5 ↗
59. Song S, Wu K, Wu H et al (2019) Multi-shelled ZnO decorated with nitrogen and phosphorus co-doped carbon quantum dots: synthesis and enhanced photodegradation activity of methylene blue in aqueous solutions. RSC Adv 9:7362–7374. https://doi.org/10.1039/c9ra00168a10.1039/c9ra00168a ↗
60. Wen XJ, Niu CG, Zhang L (2017) Fabrication of SnO2 nanoparticles/BiOI n–p heterostructure for wider spectrum visible-light photocatalytic degradation of antibiotic oxytetracycline hydrochloride. ACS Sustain Chem Eng 5:5134–5147. https://doi.org/10.1021/acssuschemeng.7b0050110.1021/acssuschemeng.7b00501 ↗
61. Zhang G, Chen D, Li N et al (2019) Fabrication of Bi2MoO6/ZnO hierarchical heterostructures with enhanced visible-light photocatalytic activity. Appl Catal B Environ 250:313–324. https://doi.org/10.1016/j.apcatb.2019.03.05510.1016/j.apcatb.2019.03.055 ↗
62. Zhang LS, Wong KH, Yip HY et al (2010) Effective photocatalytic disinfection of E. coli K-12 using AgBr-Ag-Bi2WO6 nanojunction system irradiated by visible light the role of diffusing hydroxyl radical. Environ Sci Technol 44:1392–1398. https://doi.org/10.1021/es903087w10.1021/es903087w ↗
63. Zhang H, Zong RL, Zhao JC et al (2008) Dramatic visible photocatalytic degradation performances due to synergetic effect of TiO2 with PANI. Environ Sci Technol 42:3803–3807. https://doi.org/10.1021/es703037x10.1021/es703037x ↗
64. Huang H, He Y, Li X et al (2015) Bi2O2(OH)(NO3) as a desirable [Bi2O2]2+ layered photocatalyst: strong intrinsic polarity, rational band structure and active facets co-beneficial for robust photooxidation capability. J Mater Chem A 3:24547–24556. https://doi.org/10.1039/c5ta07655b10.1039/c5ta07655b ↗
65. Siddiqui SI, Manzoor O, Mohsin M, Chaudhry SA (2019) Nigella sativa seed based nanocomposite-MnO2/BC: an antibacterial material for photocatalytic degradation, and adsorptive removal of Methylene blue from water. Environ Res 171:328–340. https://doi.org/10.1016/j.envres.2018.11.04410.1016/j.envres.2018.11.044 ↗
66. Singh R, Kumar M, Tashi L, Khajuria H, Sheikh HN (2019) Hydrothermal synthesis of manganese oxide and nitrogen doped graphene (NG-MnO2) nanohybrid for visible light degradation of methyl orange dye. Mol Phys 117:2477–2486. https://doi.org/10.1080/00268976.2019.156785410.1080/00268976.2019.1567854 ↗
67. Jiao Y, Huang Q, Wang J et al (2019) A novel MoS2 quantum dots (QDs) decorated Z-scheme g-C3N4 nanosheet/N-doped carbon dots heterostructure photocatalyst for photocatalytic hydrogen evolution. Appl Catal B Environ 247:124–132. https://doi.org/10.1016/j.apcatb.2019.01.07310.1016/j.apcatb.2019.01.073 ↗