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

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


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)


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.


Supplementary information

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


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  • 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.

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