logo

SCIENCE CHINA Materials, Volume 61, Issue 6: 861-868(2018) https://doi.org/10.1007/s40843-017-9171-9

Novel Cu3P/g-C3N4 p-n heterojunction photocatalysts for solar hydrogen generation

More info
  • ReceivedOct 30, 2017
  • AcceptedNov 28, 2017
  • PublishedJan 15, 2018

Abstract

Developing efficient heterostructured photocatalysts to accelerate charge separation and transfer is crucial to improving photocatalytic hydrogen generation using solar energy. Herein, we report for the first time that p-type copper phosphide (Cu3P) coupled with n-type graphitic carbon nitride (g-C3N4) forms a p-n junction to accelerate charge separation and transfer for enhanced photocatalytic activity. The optimized Cu3P/g-C3N4 p-n heterojunction photocatalyst exhibits 95 times higher activity than bare g-C3N4, with an apparent quantum efficiency of 2.6% at 420 nm. A detail analysis of the reaction mechanism by photoluminescence, surface photovoltaics and electrochemical measurements revealed that the improved photocatalytic activity can be ascribed to efficient separation of photo-induced charge carriers. This work demonstrates that p-n junction structure is a useful strategy for developing efficient heterostructured photocatalysts.


Funded by

The authors thank the financial support from the National Natural Science Foundation of China(21606175)

the grant support from the China Postdoctoral Science Foundation(2014M560768)

the China Fundamental Research Funds for the Central Universities(xjj2015041)


Acknowledgment

The authors thank the financial support from the National Natural Science Foundation of China (21606175), the grant support from China Postdoctoral Science Foundation (2014M560768), and China Fundamental Research Funds for the Central Universities (xjj2015041).


Interest statement

The authors declare no conflict of interest.


Contributions statement

Chen Y and Qin Z designed the project; Qin Z, Wang M, and Li R performed the experiments; Chen Y and Qin Z wrote the paper. All authors contributed to the general discussion.


Author information

Zhixiao Qin received his bachelor degree from Xi’an Jiaotong University in 2013. He is currently a PhD student at Xi’an Jiaotong University. His research interests focus on photocatalytic and photoelectrochemical water splitting.

Yubin Chen is an associate professor at Xi’an Jiaotong University. He received his bachelor degree in 2007 and PhD degree in 2013 from Xi’an Jiaotong University. From 2011 to 2012, he studied at Case Western Reserve University as a visiting scholar. His current research interests focus on photocatalysis, water splitting and functional nanomaterials for energy conversion.

Supplement

Supplementary information

Supporting data are available in the online version of the paper.


References

[1] Gray HB. Powering the planet with solar fuel. Nat Chem, 2009, 1: 7 CrossRef ADS Google Scholar

[2] Fujishima A, Honda K. Electrochemical photolysis of water at a semiconductor electrode. Nature, 1972, 238: 37-38 CrossRef ADS Google Scholar

[3] Chen X, Shen S, Guo L, et al. Semiconductor-based photocatalytic hydrogen generation. Chem Rev, 2010, 110: 6503-6570 CrossRef Google Scholar

[4] Tong H, Ouyang S, Bi Y, et al. Nano-photocatalytic materials: possibilities and challenges. Adv Mater, 2012, 24: 229-251 CrossRef Google Scholar

[5] Zhang K, Guo L. Metal sulphide semiconductors for photocatalytic hydrogen production. Catal Sci Technol, 2013, 3: 1672-1690 CrossRef Google Scholar

[6] Su J, Zhou J, Wang L, et al. Synthesis and application of transition metal phosphides as electrocatalyst for water splitting. Sci Bull, 2017, 62: 633-644 CrossRef Google Scholar

[7] Wang X, Maeda K, Thomas A, et al. A metal-free polymeric photocatalyst for hydrogen production from water under visible light. Nat Mater, 2009, 8: 76-80 CrossRef ADS Google Scholar

[8] Liu G, Wang T, Zhang H, et al. Nature-inspired environmental “phosphorylation” boosts photocatalytic H2 production over carbon nitride nanosheets under visible-light irradiation. Angew Chem, 2015, 127: 13765-13769 CrossRef Google Scholar

[9] Liu J, Liu Y, Liu N, et al. Metal-free efficient photocatalyst for stable visible water splitting via a two-electron pathway. Science, 2015, 347: 970-974 CrossRef ADS Google Scholar

[10] Li Y, Xu H, Ouyang S, et al. In situ surface alkalinized g-C3N4 toward enhancement of photocatalytic H2 evolution under visible-light irradiation. J Mater Chem A, 2016, 4: 2943-2950 CrossRef Google Scholar

[11] Ong WJ, Tan LL, Ng YH, et al. Graphitic carbon nitride (g-C3N4 )- based photocatalysts for artificial photosynthesis and environmental remediation: are we a step closer to achieving sustainability?. Chem Rev, 2016, 116: 7159-7329 CrossRef Google Scholar

[12] Qin Z, Chen Y, Wang X, et al. Intergrowth of cocatalysts with host photocatalysts for improved solar-to-hydrogen conversion. ACS Appl Mater Interfaces, 2016, 8: 1264-1272 CrossRef Google Scholar

[13] Chang K, Mei Z, Wang T, et al. MoS2/Graphene cocatalyst for efficient photocatalytic H2 evolution under visible light irradiation. ACS Nano, 2014, 8: 7078-7087 CrossRef Google Scholar

[14] Yang J, Wang D, Han H, et al. Roles of cocatalysts in photocatalysis and photoelectrocatalysis. Acc Chem Res, 2013, 46: 1900-1909 CrossRef Google Scholar

[15] Maeda K, Wang X, Nishihara Y, et al. Photocatalytic activities of graphitic carbon nitride powder for water reduction and oxidation under visible light. J Phys Chem C, 2009, 113: 4940-4947 CrossRef Google Scholar

[16] Chen Y, Qin Z. General applicability of nanocrystalline Ni2P as a noble-metal-free cocatalyst to boost photocatalytic hydrogen generation. Catal Sci Technol, 2016, 6: 8212-8221 CrossRef Google Scholar

[17] Yi SS, Yan JM, Wulan BR, et al. Noble-metal-free cobalt phosphide modified carbon nitride: an efficient photocatalyst for hydrogen generation. Appl Catal B-Environ, 2017, 200: 477-483 CrossRef Google Scholar

[18] Indra A, Acharjya A, Menezes PW, et al. Boosting visible-light-driven photocatalytic hydrogen evolution with an integrated nickel phosphide-carbon nitride system. Angew Chem Int Ed, 2017, 56: 1653-1657 CrossRef Google Scholar

[19] Zhao H, Sun S, Jiang P, et al. Graphitic C3N4 modified by Ni2P cocatalyst: an efficient, robust and low cost photocatalyst for visible-light-driven H2 evolution from water. Chem Eng J, 2017, 315: 296-303 CrossRef Google Scholar

[20] Sun Z, Zheng H, Li J, et al. Extraordinarily efficient photocatalytic hydrogen evolution in water using semiconductor nanorods integrated with crystalline Ni2P cocatalysts. Energy Environ Sci, 2015, 8: 2668-2676 CrossRef Google Scholar

[21] Cao S, Chen Y, Wang CJ, et al. Spectacular photocatalytic hydrogen evolution using metal-phosphide/CdS hybrid catalysts under sunlight irradiation. Chem Commun, 2015, 51: 8708-8711 CrossRef Google Scholar

[22] Sun Z, Yue Q, Li J, et al. Copper phosphide modified cadmium sulfide nanorods as a novel p-n heterojunction for highly efficient visible-light-driven hydrogen production in water. J Mater Chem A, 2015, 3: 10243-10247 CrossRef Google Scholar

[23] Yue X, Yi S, Wang R, et al. A novel and highly efficient earth-abundant Cu3P with TiO2 “P-N” heterojunction nanophotocatalyst for hydrogen evolution from water. Nanoscale, 2016, 8: 17516-17523 CrossRef Google Scholar

[24] Qin Z, Xue F, Chen Y, et al. Spatial charge separation of one-dimensional Ni2P-Cd0.9Zn0.1S/g-C3N4 heterostructure for high-quantum-yield photocatalytic hydrogen production. Appl Catal B-Environ, 2017, 217: 551-559 CrossRef Google Scholar

[25] Chen Y, Qin Z, Wang X, et al. Noble-metal-free Cu2S-modified photocatalysts for enhanced photocatalytic hydrogen production by forming nanoscale p-n junction structure. RSC Adv, 2015, 5: 18159-18166 CrossRef Google Scholar

[26] Chen Y, Wang L, Lu GM, et al. Nanoparticles enwrapped with nanotubes: a unique architecture of CdS/titanate nanotubes for efficient photocatalytic hydrogen production from water. J Mater Chem, 2011, 21: 5134-5141 CrossRef Google Scholar

[27] Meng F, Li J, Cushing SK, et al. Solar hydrogen generation by nanoscale p-n junction of p-type molybdenum disulfide/n-type nitrogen-doped reduced graphene oxide. J Am Chem Soc, 2013, 135: 10286-10289 CrossRef Google Scholar

[28] Manna G, Bose R, Pradhan N. Semiconducting and plasmonic copper phosphide platelets. Angew Chem Int Ed, 2013, 52: 6762-6766 CrossRef Google Scholar

[29] Ni S, Ma J, Lv X, et al. The fine electrochemical performance of porous Cu3P/Cu and the high energy density of Cu3P as anode for Li-ion batteries. J Mater Chem A, 2014, 2: 20506-20509 CrossRef Google Scholar

[30] Villevieille C, Robert F, Taberna PL, et al. The good reactivity of lithium with nanostructured copper phosphide. J Mater Chem, 2008, 18: 5956-5960 CrossRef Google Scholar

[31] Liang Q, Li Z, Yu X, et al. Macroscopic 3D porous graphitic carbon nitride monolith for enhanced photocatalytic hydrogen evolution. Adv Mater, 2015, 27: 4634-4639 CrossRef Google Scholar

[32] Xiong J, Wang Y, Xue Q, et al. Synthesis of highly stable dispersions of nanosized copper particles using L-ascorbic acid. Green Chem, 2011, 13: 900-904 CrossRef Google Scholar

[33] Butler MA. Photoelectrolysis and physical properties of the semiconducting electrode WO2. J Appl Phys, 1977, 48: 1914-1920 CrossRef ADS Google Scholar

[34] Zhang G, Lan ZA, Lin L, et al. Overall water splitting by Pt/g-C3N4 photocatalysts without using sacrificial agents. Chem Sci, 2016, 7: 3062-3066 CrossRef Google Scholar

[35] Chen Z, Berciaud Ś, Nuckolls C, et al. Energy transfer from individual semiconductor nanocrystals to graphene. ACS Nano, 2010, 4: 2964-2968 CrossRef Google Scholar

[36] Han C, Wu L, Ge L, et al. AuPd bimetallic nanoparticles decorated graphitic carbon nitride for highly efficient reduction of water to H2 under visible light irradiation. Carbon, 2015, 92: 31-40 CrossRef Google Scholar

[37] Bi L, Xu D, Zhang L, et al. Metal Ni-loaded g-C3N4 for enhanced photocatalytic H2 evolution activity: the change in surface band bending. Phys Chem Chem Phys, 2015, 17: 29899-29905 CrossRef ADS Google Scholar

[38] Cao S, Low J, Yu J, et al. Polymeric photocatalysts based on graphitic carbon nitride. Adv Mater, 2015, 27: 2150-2176 CrossRef Google Scholar

[39] Qin Z, Chen Y, Huang Z, et al. Composition-dependent catalytic activities of noble-metal-free NiS/Ni3S4 for hydrogen evolution reaction. J Phys Chem C, 2016, 120: 14581-14589 CrossRef Google Scholar

[40] Zhang J, Qi L, Ran J, et al. Ternary NiS/Znx Cd1-xS/reduced graphene oxide nanocomposites for enhanced solar photocatalytic H2-production activity. Adv Energy Mater, 2014, 4: 1301925 CrossRef Google Scholar

[41] Chen J, Shen S, Guo P, et al. In-situ reduction synthesis of nano-sized Cu2O particles modifying g-C3N4 for enhanced photocatalytic hydrogen production. Appl Catal B-Environ, 2014, 152-153: 335-341 CrossRef Google Scholar

[42] Chen Y, Qin Z, Chen T, et al. Optimization of (Cu2Sn)xZn3(1−x)S3/CdS pn junction photoelectrodes for solar water reduction. RSC Adv, 2016, 6: 58409-58416 CrossRef Google Scholar

[43] Kronik L, Shapira Y. Surface photovoltage phenomena: theory, experiment, and applications. Surf Sci Rep, 1999, 37: 1-206 CrossRef ADS Google Scholar

  • Figure 1

    XRD patterns of Cu3P, g-C3N4, and Cu3P/g-C3N4.

  • Figure 2

    (a) TEM and (b) HRTEM images of Cu3P/g-C3N4. (c) Elemental mapping of C, N, Cu, and P species in Cu3P/g-C3N4 (excess C and Cu signals came from the carbon film on the copper grid).

  • Figure 3

    XPS spectra of Cu3P/g-C3N4. (a) C 1s, (b) N 1s, (c) Cu 2p, and (d) P 2p.

  • Figure 4

    UV-vis absorption spectra of (a) g-C3N4, Cu3P/g-C3N4 and (b) Cu3P. The insets show the plots of (αhν)1/2 vs. photon energy () for g-C3N4 and (αhν)2 vs. for Cu3P.

  • Figure 5

    (a) Photocatalytic hydrogen evolution rates of g-C3N4, Cu3P/g-C3N4 (the loading amount of Cu3P was respectively 0.5, 1, 3, and 5 wt%), Cu3P, and physically mixed Cu3P@g-C3N4 (the loading amount of Cu3P was 1 wt%). (b) Long-time photocatalytic test of 1 wt% Cu3P/g-C3N4 sample for hydrogen evolution. (Reaction condition: 20 mg of photocatalysts, 80 mL of aqueous solution containing 10 vol% TEOA, 300 W Xe lamp equipped with a cutoff filter (λ420 nm).

  • Figure 6

    (a) PL spectra of g-C3N4 and Cu3P/g-C3N4. (b) SPV spectra of g-C3N4 and Cu3P/g-C3N4. The inset shows the schematic setup for the SPV measurement.

  • Figure 7

    (a) Nyquist impedance plots of g-C3N4 and Cu3P/g-C3N4 measured at −1.0 V vs. RHE in N2-saturated 0.5 mol L−1 Na2SO4 aqueous solution. The inset shows the equivalent circuit. (b) Transient photocurrent responses of g-C3N4 and Cu3P/g-C3N4 measured at 0.2V vs. RHE in N2-saturated 0.5 mol L−1 Na2SO4 aqueous solution. A 500 W Xe lamp coupled with an AM 1.5 filter was used as the light source for the photocurrent measurement.

  • Figure 8

    XPS valence band spectra for (a) g-C3N4 and (b) Cu3P. Mott-Schottky plots of (c) g-C3N4 and (d) Cu3P in N2-saturated 0.5 mol L−1 Na2SO4 aqueous solution.

  • Figure 9

    (a) Energy band structures of Cu3P and g-C3N4 before formation of the heterojunction. (b) The band structure for Cu3P/g-C3N4 heterojunction and charge separation process under illumination.

Copyright 2019 Science China Press Co., Ltd. 《中国科学》杂志社有限责任公司 版权所有

京ICP备18024590号-1