Synergistic impact of cocatalysts and hole scavenger for promoted photocatalytic H2 evolut - 论文 

Journal of Energy Chemistry 32 (2019) 45-56Contents lists available at ScienceDirectJournal of Energy ChemistryELSEVIERjournal homepage: www.elsevier.com/locate/jechemJGC■IOURNAI OF WNGRGY CHeMISTRYhttp://www.journals.elsevier.com/

journal-of-energy-chemistry/Synergistic impact of cocatalysts and hole scavenger for promoted photocatalytic H2 evolution in mesoporous TiO2-NiSx hybridYi Weia, Gang Cheng3**, Jinyan Xiongbd, Jiaxin Zhua, Yixin Gana, Mengmeng Zhang9, Zhen Lic, Shixue Douda School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430073, Hubei, Chinab College of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan 430200, Hubei, Chinac School of Radiation Medicine and Radiation Protection, Collaborative Innovation Center of Radiation Medicine ofJiangsu Higher Education Institutions. Soochow University, Suzhou 215123, Jiangsu, Chinad Institute for Superconducting and Electronic Materials, University of Wollongong. North Wollongong NSW2500, AustraliaARTICLE INFOArticle history:Received 27 February 2018Revised 10 May 2018Accepted 24 May 2018

Available online 31 May 2018ABSTRACTKeywords:NiS/Ni3S4CocatalystPhotocatalytic hydrogen evolutionMesoporous TiO2Hole scavengerPhotocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic im-pact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3% (mole ratio of Ni2+) NiSx co-catalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 pmol h i g-' which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.? 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published

by Elsevier B.V. and Science Press. All rights reserved.1. IntroductionSemiconductor-based photocatalytic hydrogen evolution to-wards water splitting has been regarded as one green technique for solar energy conversion to meet the growing global energy demand. Upon the light irradiation, a semiconductor nanocrystal would absorb photons with energy higher than its band gap and then generate the photo-induced electrons and holes. At the same time, the photogenerated charges migrated on the surface of the semiconductor and accordingly initiated the superficial redox re-action [1]. In the past decades, TiO2-based nanocrystals have at-tracted increasing interest in solar energy photocatalysis owing to its low cost, nontoxicity, good chemical stability and suitable band energy level for water splitting [2,3]. However, bare TiO2 usually exhibits poor photocatalytic hydrogen evolution performance due to a fast recombination of electron-hole pairs produced under light excitation [3,4|. Hence, tremendous efforts have been paid to ad-dressing the above issue through morphology tailoring [5], elementCorresponding author.E-mail address: gcheng@wit.edu.cn (G. Cheng).

doping [6] and cocatalyst modification [7,8], of which a su让able co-catalyst modification has been extensively used because it not only acts as electron sink to accelerate the charge separation, but also could serve as active sites to reduce the hydrogen production over- potential [9,10).Compared to high cost noble metal and metal oxides (Pt, Pd, RuO2, etc.) [11 ], the earth-abundant cocatalysts based on cobalt, copper, molybdenum, and nickel have been intensively studied in recent years [12,13]. In heterogeneous catalysis, an optimal cat-alytic activity could be achieved on catalytic surface with interme-diate free energy of adsorption for reactive in termediate. Accord-ing to the density functional theory (DFT) calculations reported by Greely et al. [14], the hydrogen evolution activity could be opti-mized on the surface of nickel-based electrocatalysts, because of their suitable hydrogen intermediate binding energy. It indicates that nickel-based cocatalysts could exhibit great potential in pho-tocatalytic hydrogen evolution, which has been confirmed by the recent reports on nickel-based cocatalysts, in eluding Ni [15,16], Ni2P [17], Ni(0H)2 [5,18], Ni(HCO3)2 [19| and NiS [20,21], which could promote the photocatalytic hydrogen evolution capability of the host semiconductor photocatalysts. These reports are fo-cused on single nickel-based cocatalysts, while there are few re-

https://doi.org/10.1016/jjechem.2018.05.0132095-4956/? 2018 Science Press and Dalian Institute of Chemical Physics. Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.