Hydrogen production from water splitting on CdS-based photocatalysts using solar light

Abstract

Hydrogen energy has been regarded as the most promising energy resource in the near future due to that it is a clean and sustainable energy. And the heterogeneous photocatalytic hydrogen production is increasingly becoming a research hotspot around the world today. As visible light response photocatalysts for hydrogen production, cadmium sulfide (CdS) is the most representative material, the research of which is of continuing popularity. In the past several years, there has been significant progress in water splitting on CdS-based photocatalysts using solar light, especially in the development of co-catalysts. In this paper, recent researches into photocatalytic water splitting on CdS-based photocatalysts are reviewed, including controllable synthesis of CdS, modifications with different kinds of cocatalysts, solid solution, intercalated with layered nanocomposites and metal oxides, and hybrids with graphenes etc. Finally, the problems and future challenges in photocatalytic water splitting on CdS-based photocatalysts are described.

Keywords

hydrogen / photocatalysis / solar conversion / cadmium sulfide (CdS) complex

Introduction

As fossil fuels are likely to be exhausted in the near future and bring lots of serious environmental problems, hydrogen, a new renewable and no-polluting energy, has been considered as a promising candidate to solve these problems. There are different ways to get hydrogen from water such as electrolysis of water, but most of them are costly. In various interesting reactions, the hydrogen production from photocatalytic water splitting by sunlight is potentially one of the most promising ways for the photochemical conversion and storage of solar energy. Since the evolution of hydrogen and oxygen on TiO₂ and Pt counter electrodes under the irradiation of ultraviolet (UV) light was reported by Fujishima and Honda in 1972 [1], photocatalysis has been receiving much attention and studies have been extensively conducted on converting solar energy into clean hydrogen energy. The mechanism of photocatalytic of water is illustrated in Fig. 1, in which TiO₂ was taken as an example [2]. The band gap (between valance band and conductance band) of TiO₂ is approximately 3.0 eV. Electronic transition from valance band to conductance band can be activated by light radiation whose energy should be greater than or equal to its band gap. Consequently, the electron and hole pairs are formed in conductance band and valance band, which can decompose water into hydrogen and oxygen respectively. Up to the present, various kinds of efficient hydrogen-evolution photocatalysts have been reported which can mainly be divided into the titanium dioxide system [3–7] which also contains hybrids of TiO₂ [8,9]; metal sulfides, nitrides and phosphides [10–13]; the tantalate and niobate system [14–18]; and composite catalysts [19–23]. However, most of these photocatalysts are only active under UV light, which accounts for only approximately 3%–5% of the solar spectrum on the surface of the earth.

Cadmium sulfide (CdS) has a band-gap energy (E_g) of 2.4 eV that suits very well with the solar spectrum as shown in Fig. 2, which has received much attention and has been studied widely. However, CdS is not stable in aqueous solutions under irradiation due to photocorrosion. Furthermore, the photocatalytic activity of individual CdS is not so efficient. In order to solve these problems, many researchers mainly focus their attention on material preparation, where different morphology and crystal CdS are synthetized; material modifications; and the system of photocatalytic water splitting to improve the photoactivity.

In this paper, the current research focuses on the improvement of CdS photocatalytic activity are reviewed and discussed. In addition, future trends of research on photocatalytic water splitting with CdS are presented.

Controllable synthesis of CdS for photocatalytic hydrogen evolution

The photocatalytic properties of CdS semiconductor materials depend not only on the particle size but also the morphology [25–27]. So different synthesis methods are attempted to prepare CdS with different nanostructured and high BET surface area for improving its photoactivity [28–32]. Liu et al. [28] have prepared CdS hollow nanoparticle chains through a facile and efficient ultrasonic-template method. Other shapes of CdS nanostructures, such as nanorods, hollow nanorods, multipods, quasi-nanospheres, hollow nanospheres, nanoshuttles, nanowires, nanotubes, nanosheets have also been reported [29–32]. Li et al. [31] have obtained solid nanospheres (s-CdS), hollow nanospheres (h-CdS) and nanorods (r-CdS) by controlling only the hydrothermal temperatures. They have also revealed the performance of different hydrogen evolutions as presented in Fig. 3. Bao et al. [32] synthesized porous nanosheets and hollow nanorods CdS by a two-step aqueous route. The quantum yield could come to 60.34% at 420 nm after loaded with Pt.

Quantum dots are also used to improve the photocatalytic acivity of catalysts because of its special properties. Yu et al. [33] prepared CdS quantum dots-sensitized Zn_1-xCd_xS solid solutions by a simple cation exchange. It showed high visible-light photocatalytic H₂-production activity even without a Pt co-catalyst.

Modifications of CdS

Loaded with cocatalysts

Besides preparing CdS with different morphology and particle size, co-catalysts also play an important role in stimulating charge transfer and reducing the recombination of photo-induced charges, thereby enhancing the photocatalytic activity of CdS. The efficient photocatalytic co-catalysts usually contain noble metals (Pt, Au, Rh, RuO₂, etc.) [34–39]. Luo et al. [39] have prepared CdS loaded with dual co-catalysts including PdS and Pt as the oxidation and reduction co-catalysts, respectively. As demonstrated in Fig. 4, electrons and holes can be transferred at the same time. The quantum efficiency of photocatalytic hydrogen production can reach 93% in the presence of sacrificial reagents under visible light.

Although good photocatalytic performance of CdS can be achieved in the presence of noble metals co-catalysts, it is necessary to explore non-noble metals to reduce the cost of renewable H₂ production. The traditional efficient non-noble metals co-catalysts are nickels (Ni, NiO, NiS, NiO_x) [38–40]. However, several researches have focused on the modification of CdS with metal sulfides (MoS₂, WS₂) recently, which supplies a new way to improve the performance of CdS [41,42]. MoS₂ is an excellent H₂ evolution co-catalyst. Furthermore, the junctions formed between MoS₂ and CdS also play an important role in enhancing the photocatalytic activity of CdS. Thus, the 0.2 wt% MoS₂/CdS catalyst demonstrates even higher activity than other noble metal co-catalysts as tabulated in Table 1 [42]. W₂S plays the same role as MoS₂ in enhancing the photocatalytic activity of CdS [41].

Intercalated with layered nanocomposites and metal oxides

In order to improve the photocatalytic properties, CdS nanoparticles are often incorporated in the interlayer of some particulate metal oxides. As shown in Fig. 5, the incorporation of CdS nanoparticles into the interlayer of layered metal oxides suppresses particle growth while nanoheterojunctions are formed easily between the host layer and the CdS. Thus, photogenerated electrons are quickly transferred through the nanostructure while the recombination between the photo-induced electron and the hole is effectively suppressed. Consequently, the photocatalytic evolution of hydrogen is enhanced [38].

As listed in Table 2, the photocatalytic hydrogen evolution of CdS intercalated with layered nanocomposites is superior to simple CdS and the physical mixture of CdS and metal oxides. Further, the activity of CdS intercalated with layered nanocomposites is dependent on hostlayer. The substitution of Nb for partial Ti can bring the quick transfer of the electrons photogenerated in CdS through the host layer into the surface of photocatalysts, Thus, the hydrogen evolution increases [38].

Recently, the Z-scheme has been investigated to split water into hydrogen and oxygen [43,44]. Tada et al. [45] have designed a CdS-Au-TiO₂ three-component nanojunction system imitating natural photosynthesis. This three-component system exhibit a high photocatalytic activity, far exceeding those of the single- and two-component systems, as a result of vectorial electron transfer driven by the two-step excitation of TiO₂ and CdS.

Other CdS intercalated with metal oxides or sulfides and the heterojunction between them have also been extensively studied [46–51]. Barpuzary et al. [51] have prepared high surface area CdS using Al₂O₃ and ZnO as templates by a hydrothermal route. The apparent quantum yields of hetero-system-based CdS@Al₂O₃ and CdS@ZnO can account to 11% and 15% respectively. One-dimensional heterostructures of CdS nanowires decorated with hematite nanoparticles and magnetite microsphere have been synthesized via a two-step solvothermal deposition method [52]. The enhanced photocatalytic activity under visible light happens on account of the help of heterostructures, which can facilitate charge separation. Li et al. [53] have fabricated CdS/TiO₂NTs in which CdS is incorporated into the TiO₂ nanotubes homogeneously. Because of the quantum size effect and the potential gradient at the interface between CdS nanoparticles and TiO₂ nanotubes, the CdS/TiO₂NTs showed higher activity for hydrogen production under visible light.

Solid solution

The solid solution is often used as an efficient way to improve the activity and stability of CdS [54–57]. With the help of insert metals, the electron-hole recombination and photocorrosion can be prevented efficiently. Therefore, the photocatalytic activity and stability of catalysts can be enhanced apparently [55]. For instance, Ikeue et al. [56] have synthesized the composite sulfide system (Mn_1-xCd_xS) by a hydrothermal method and found that the high photocatalytic activity of the Mn_1-xCd_xS system is caused by low-crystalline. Moreover, Mn_1-xCd_xS system showed better tolerance to photocorrosion compared to single CdS. On the other hand, the band structure of Mn_1-xCd_xS system could also be controlled through controlling components and their contents of solid solution. As is known, the band gap of CdS and ZnS are 2.20 and 3.12 eV respectively. And the band gap position of the solid solutions can be adjusted by changing the ratio of the composition of CdS to that of ZnS as displayed in Fig. 6 [54], which is important for high efficient and stable photocatalysts design and preparation.

Hybrids with graphenes

Because of the special conductivity and conjugated system derived from the unique sp² hybrid carbon skeleton structure, graphene has been regarded as an ideal conductive support for nanoparticles to form hybrid materials with CdS for the purpose of photocatalytic activity improvement [58–62]. As exhibited in Fig. 7, CdS or its solid solutions can be excited by solar to generate electrons and holes. Besides the function of heterostructures and high surface area of catalyst hybrids, the photogenerated electrons are transferred to graphene while holes are left in CdS since the conduction band of CdS is more negative [59]. Thus, the recombination of electron-hole pairs is suppressed and the lifetime of charge carriers is prolonged. Consequently, the photoactivity can be improved efficiently and the apparent quantum efficiency can be up to 23.4% at 420 nm [58].

Conclusions

In this paper, current researches of hydrogen production with CdS-based photocatalysts are reviewed and discussed. Great progress has been made in the research of high efficient photocatalytic hydrogen production with CdS. Through loading cocatalysts, intercalating with layered nanocomposites, hybrids with graphenes or solid solution can favor electron transfer and suppress the recombination of electron-hole pairs. Thus the photocatalytic activity and stability can be improved apparently. These may provide reference for the preparation of more efficient CdS-based photocatalysts for the purpose of hydrogen production. However, few studies on suppressing photocorrosion have been conducted to improve the stability of CdS. Consequently, new and advanced ways have to be further investigated on CdS to enhance its photocatalytic water splitting performance.

References

[1] Fujishima A, Honda K. Electrochemical photolysis of water at a semiconductor electrode. Nature, 1972, 238(5358): 37–38

[2] Shangguan W F. Progress in hydrogen production from water splitting using solar light. Chinese Journal of Inorganic Chemistry, 2001, 17(5): 619–624

[3] Hosono E, Fujihara S, Imai H, Honma I, Masaki I, Zhou H S. One-step synthesis of nano-micro chestnut TiO₂ with rutile nanopins on the microanatase octahedron. ACS Nano, 2007, 1(4): 273–278

[4] Chuangchote S, Jitputti J, Sagawa T, Yoshikawa S. Photocatalytic activity for hydrogen evolution of electrospun TiO₂ nanofibers. ACS Applied Materials & Interfaces, 2009, 1(5): 1140–1143

[5] Weng C C, Hsu K F, Wei K H. Synthesis of arrayed TiO₂ needlelike nanostructures via a polystyrene-block-poly (4-vinylpyridine) diblock copolymer template. Chemistry of Materials, 2004, 16(21): 4080–4086

[6] Wang H Q, Wu Z B, Liu Y. A simple two-step template approach for preparing carbon-doped mesoporous TiO₂. Journal of Physical Chemistry C, 2009, 113(30): 13317–13324

[7] Wang D A, Liu Y, Wang C W, Zhou F, Liu W M. Highly flexible coaxial nanohybrids made from porous TiO₂ nanotubes. ACS Nano, 2009, 3(5): 1249–1257

[8] Irie H, Watanabe Y, Hashimoto K. Nitrogen-concentration dependence on photocatalytic activity of TiO_2-xN_x powders. Journal of Physical Chemistry B, 2003, 107(23): 5483–5486

[9] Khan S U, Al-Shahry M, Ingler W B Jr. Efficient photochemical water splitting by a chemically modified n-TiO₂. Science, 2002, 297(5590): 2243–2245

[10] Yan H J, Yang J H, Ma G J, Wua G P, Zong X, Lei Z B, Shi J Y, Li C. Visible-light-driven hydrogen production with extremely high quantum efficiency on Pt-PdS/CdS photocatalys. Journal of Catalysis, 2009, 266(2): 165–168

[11] Maeda K, Saito N, Lu D, Inoue Y, Domen K. Photocatalytic properties of RuO₂-loaded β-Ge₃N₄ for overall water splitting. Journal of Physical Chemistry C, 2007, 111(12): 4749–4755

[12] Hara M, Hitoki G, Takata T, Kondo J N, Kobayashi H, Domen K. TaON and Ta₃N₅ as new visible light driven photocatalysts. Catalysis Today, 2003, 78(1–4): 555–560

[13] Ohmori T, Mametsuka H, Suzuki E. Photocatalytic hydrogen evolution on InP suspension with inorganic sacricial reducing agent. International Journal of Hydrogen Energy, 2000, 25(10): 953–955

[14] Kato H, Asakura K, Kudo A. Highly efficient water splitting into H₂ and O₂ over lanthanum-doped NaTaO₃ photocatalysts with high crystallinity and surface nanostructure. Journal of the American Chemical Society, 2003, 125(10): 3082–3089

[15] Yoshioka K, Petrykin V, Kakihana M, Kato H, Kudo A. The relationship between photocatalytic activity and crystal structure in strontium tantalates. Journal of Catalysis, 2005, 232(1): 102–107

[16] Domen K, Kudo A, Tanaka A, Onishi T. Overall photodecomposition of water on a layered niobiate catalyst. Catalysis Today, 1990, 8(1): 77–84

[17] Wang D F, Zou Z G, Ye J H. A new spinel-type photocatalyst BaCr₂O₄ for H₂ evolution under UV and visible light irradiation. Chemical Physics Letters, 2003, 373(1–2): 191–196

[18] Zou Z G, Ye J H, Arakawa H. Role of R in Bi₂RNbO₇ (R= Y, Rare Earth): Effect on band structure and photocatalytic properties. Journal of Physical Chemistry, 2002, 106(3): 517–520

[19] Maeda K, Teramura K, Lu D L, Takata T, Saito N, Inoue Y, Domen K. Photocatalyst releasing hydrogen from water. Nature, 2006, 440(7082): 295

[20] Wang X C, Maeda K, Lee Y, Domen K. Enhancement of photocatalytic activity of (Zn_1+xGe)(N₂O_x) for visible-light-driven overall water splitting by calcination under nitrogen. Chemical Physics Letters, 2008, 457(1–3): 134–136

[21] Tsuji I, Kato H, Kobayashi H, Kudo A. Photocatalytic H₂ evolution reaction from aqueous solutions over band structure-controlled (AgIn)_xZn_2(1-x)S₂ solid solution photocatalysts with visible-light response and their surface nanostructures. Journal of the American Chemical Society, 2004, 126(41): 13406–13413

[22] Liu H, Yuan J, Shangguan W F, Teraoka Y. Visible-light-responding BiYWO₆ solid solution for stoichiometric photocatalytic water splitting. Journal of Physical Chemistry C, 2008, 112(23): 8521–8523

[23] Shangguan W F. Hydrogen evolution from water splitting on nanocomposite photocatalysts. Science and Technology of Advanced Materials, 2007, 8(1,2): 76–81

[24] Kudo A, Miseki Y. Heterogeneous photocatalyst materials for water splitting. Chemical Society Reviews, 2009, 38(1): 253–278

[25] Agarwal R, Barrelet C J, Lieber C M. Lasing in single cadmium sulfide nanowire optical cavities. Nano Letters, 2005, 5(5): 917–920

[26] Sathish M, Viswanathan B, Viswanath R P. Alternate synthetic strategy for the preparation of CdS nanoparticles and its exploitation for watersplitting. International Journal of Hydrogen Energy, 2006, 31(7): 891–898

[27] Grzelczak M, Correa-Duarte M A, Salgueirino-Maceira V, Giersig M, Diaz R, Liz-Marzán L M. Photoluminescence quenching control in quantum dot-carbon nanotube composite colloids using a silica-shell spacer. Advanced Materials (Deerfield Beach, Fla.), 2006, 18(4): 415–420

[28] Liu J K, Luo C X, Yang X H, Zhang X Y. Ultrasonic-template method synthesis of CdS hollow nanoparticle chains. Materials Letters, 2009, 63(1): 124–126

[29] Wang X L, Feng Z C, Fan D Y, Fan F T, Li C. Shape-controlled synthesis of CdS nanostructures via a solvothermal method. Crystal & Growth Design, 2010, 12(12): 5312–5318

[30] Yang X H, Wu Q S, Li L, Ding Y P, Zhang G X. Controlled synthesis of the semiconductor CdS quasi-nanospheres, nanoshuttles, nanowires and nanotubes by the reverse micelle systems with different surfactants. Colloid and Surfaces A. Physicochemical and Engineering Aspects, 2005, 264(1–3): 172–178

[31] Li C L, Yuan J, Han B Y, Shangguan W F. Synthesis and photochemical performance of morphology-controlled CdS photocatalysts for hydrogen evolution under visible light. International Journal of Hydrogen Energy, 2011, 36(7): 4271–4279

[32] Bao N Z, Shen L M, Takata T, Domen K. Self-templated synthesis of nanoporous CdS nanostructures for highly efficient photocatalytic hydrogen production under visible light. Chemistry of Materials, 2008, 20(1): 110–117

[33] Yu J G, Zhang J, Jaronic M. Preparation and enhanced visible-light photocatalytic H₂-production activity of CdS quantum dots-sensitized Zn_1-xCd_xS solid solution. Green Chemistry, 2010, 12(9): 1611–1614

[34] Bao N Z, Shen L M, Takata T, Domen K, Gupta A, Yanagisawa K, Grimes C A. Facile Cd-thiourea complex thermolysis synthesis of phase-controlled CdS nanocrystals for photocatalytic hydrogen production under visible light. Journal of Physical Chemistry C, 2007, 111(47): 17527–17534

[35] Borgarello E, Kalyanasundaram K, Gratzel M. Visible light induced generation of hydrogen from H₂S in CdS-dispersions, hole transfer catalysis by RuO₂. Helvetica Chimica Acta, 1982, 65(1): 243–248

[36] Yang T T, Chen W T, Hsu Y J, Wei K H, Lin T Y, Lin T W. Interfacial charge carrier dynamics in core shell Au-CdS nanocrystals. Journal of Physical Chemistry C, 2010, 114(26): 11414–11420

[37] Yang J H, Yan H J, Wang X L, Wen F Y, Wang Z J, Fan D Y, Shi J Y, Li C. Roles of cocatalysts in Pt-PdS/CdS with exceptionally high quantum efficiency for photocatalytic hydrogen production. Journal of Catalysis, 2012, 290: 151–157

[38] Shangguan W F. Hydrogen evolution from water splitting on Nanocomposite photocatalysts. Science and Technology of Advanced Materials, 2007, 8(1,2): 76–81

[39] Luo M, Liu Y, Hu J C, Liu H, Li J L. One-pot synthesis of CdS and Ni-doped CdS hollow spheres with enhanced photocatalytic activity and durability. ACS Applied Materials & Interfaces, 2012, 4(3): 1813–1821

[40] Tabata M, Maeda K, Ishihara T, Minegishi T, Takata T, Domen K. Photocatalytic hydrogen evolution from water using copper gallium sulfide under visible-light irradiation. Journal of Physical Chemistry C, 2010, 114(25): 11215–11220

[41] Zong X, Han J F, Ma G J, Yan H J, Wu G P, Li C. Photocatalytic H₂ evolution on CdS loaded with WS₂ as cocatalyst under visible light irradiation. Journal of Physical Chemistry C, 2011, 115(24): 12202–12208

[42] Zong X, Wu G P, Yan H J, Ma G J, Shi J Y, Wen F Y, Wang L, Li C. Photocatalytic H₂ evolution on MoS₂/CdS catalysts under visible light irradiation. Journal of Physical Chemistry C, 2010, 114(4): 1963–1968

[43] Sayama K, Mukasa K, Abe R, Abe Y, Arakawa H. Stoichiometric water splitting into H₂ and O₂ using a mixture of two different photocatalysts and IO₃^-/I^- shuttle redox mediator under visible light irradiation. Chemical Communications (Cambridge), 2001, (23): 2416–2417

[44] Kato H, Hori M, Konta R, Shimodaira Y, Kudo A. Construction of Z-scheme type heterogeneous photocatalysis systems for water splitting into H₂ and O₂ under visible light irradiation. Chemistry Letters, 2004, 33(10): 1348–1349

[45] Tada H, Mitsui T, Kiyonaga T, Akita T, Tanaka K. All-solid-state Z-scheme in CdS-Au-TiO2 three-component nanojunction system. Nature Materials, 2006, 5(10): 782–786

[46] Shangguan W F, Yoshida A. Photocatalytic hydrogen evolution from water on nanocomposites incorporating cadmium sulfide into the interlayer. Journal of Physical Chemistry B, 2002, 106(47): 12227–12230

[47] Sato T, Masaki K, Sato K, Fujishiro Y, Okuwaki A. Photocatalytic properties of layered hydrous titanium oxide/CdS-ZnS nanocomposites incorporating CdS-ZnS into the interlayer. Journal of Chemical Technology and Biotechnology (Oxford, Oxfordshire), 1996, 67(4): 339–344

[48] Sato T, Sato K, Fujishiro Y, Yoshioka T, Okuwaki A. Photochemical reduction of nitrate to ammonia using layered hydrous Titanate/Cadmium sulphide nanocomposites. Journal of Chemical Technology and Biotechnology (Oxford, Oxfordshire), 1996, 67(4): 345–349

[49] Shangguan W F, Yoshida A. Synthesis and photocatalytic properties of CdS-intercalated metal oxides. Solar Energy Materials and Solar Cells, 2001, 69(2): 189–194

[50] Gao X F, Sun W T, Hu Z D, Ai G, Zhang Y L, Feng S, Li F, Peng L M. Hu Z-D, Ai G, Zhang Y-L, Feng S, Li F, Peng L-M. An efficient method to form heterojunction CdS/TiO₂ photoelectrodes using highly ordered TiO₂ nanotube array films. Journal of Physical Chemistry C, 2009, 113(47): 20481–20485

[51] Barpuzary D, Khan Z, Vinothkumar N, De M, Qureshi M. Hierarchically grown urchinlike CdS@ZnO and CdS@Al₂O₃ heteroarrays for efficient visible-light-driven photocatalytic hydrogen generation. Journal of Physical Chemistry C, 2012, 116(1): 150–156

[52] Wang L, Wei H W, Fan Y J, Gu X, Zhan J H. One-dimensional CdS/r-Fe₂O₃ and CdS/Fe₃O₄ heterostructures: epitaxial and nonepitaxial growth and photocatalytic activity. Journal of Physical Chemistry C, 2009, 113(32): 14119–14125

[53] Li C L, Yuan J, Han B Y, Jiang L, Shangguan W F. TiO₂ Nanotubes incorporated with CdS for photocatalytic hydrogen production from splitting wat_er under visible light irradiation. International Journal of Hydrogen Energy, 2010, 35(13): 7073–7079

[54] Xing C J, Zhang Y J, Yan W, Guo L J. Band structure-controlled solid solution of Cd_1-xZn_xS photocatalyst for h_ydrogen production by water splitting. International Journal of Hydrogen Energy, 2006, 31(14): 2018–2024

[55] Kimi M, Yuliati L, Shamsuddin M. Photoca_talytic hydrogen production under visible light over Cd_0.1Sn_xZn_09-2xS solid solution photocatalysts. International Journal of Hydrogen Energy, 2011, 36(16): 9453–9461

[56] Ikeue K, Shiiba S, Machida M. Novel Visible-light-driven photocatalyst based on Mn-Cd-S for efficient H₂ evolution. Chemistry of Materials, 2010, 22(3): 743–745

[57] Xie S L, Lu X H, Zhai T, Gan J Y, Li W, Xu M, Yu M H, Zhang Y M, Tong Y X. Controllable synthesis of Zn_xCd_1-xS@ZnO core-shell nanorods with enhanced photocatalytic activity. Langmuir, 2012, 28(28): 10558–10564

[58] Zhang J, Yu J G, Jaroniec M, Gong J R. Noble metal-free reduced graphene oxide-ZnxCd_1-xS nanocomposite with enhanced solar photocatalytic H₂-production performance. Nano Letters, 2012, 12(9): 4584–4589

[59] Gao P, Liu J C, Lee S, Zhang T, Sun D D. High quality graphene oxide-CdS-Pt nanocomposites for efficient photocatalytic hydrogen evolution. Journal of Materials Chemistry, 2012, 22(5): 2292–2298

[60] Lee H, Heo K, Maaroof A, Park Y, Noh S, Park J, Jian J, Lee C, Seong M J, Hong S. High-performance photoconductive channels based on (carbon nanotube)-(CdS nanowire) hybrid nanostructures. Small, 2012, 8(11): 1650–1656

[61] Jia L, Wang D H, Huang Y X, Xu A W, Yu H Q. Highly durable N-doped graphene/CdS nanocomposites with enhanced photocatalytic hydrogen evolution from water under visible light irradiation. Journal of Physical Chemistry C, 2011, 115(23): 11466–11473

[62] Gao Z Y, Liu N, Wu D P, Tao W Q, Xu F, Jiang K. Graphene-CdS composite, synthesis and enhanced photocatalytic activity. Applied Surface Science, 2012, 258(7): 2473–2478

RIGHTS & PERMISSIONS

Higher Education Press and Springer-Verlag Berlin Heidelberg