Wavelength-Dependent Solar N-2 Fixation into Ammonia and Nitrate in Pure Water

Ren, Wenju1,2; Mei, Zongwei1; Zheng, Shisheng1; Li, Shunning1; Zhu, Yuanmin3,4; Zheng, Jiaxin1; Lin, Yuan5; Chen, Haibiao1; Gu, Meng3; Pan, Feng1

2020-05-29

10.34133/2020/3750314

Research   影响因子和分区

2639-5274

2639-5274

Solar-driven N-2 fixation using a photocatalyst in water presents a promising alternative to the traditional Haber-Bosch process in terms of both energy efficiency and environmental concern. At present, the product of solar N-2 fixation is either NH4+ or NO3-. Few reports described the simultaneous formation of ammonia (NH4+) and nitrate (NO3-) by a photocatalytic reaction and the related mechanism. In this work, we report a strategy to photocatalytically fix nitrogen through simultaneous reduction and oxidation to produce NH4+ and NO3- by W18O49 nanowires in pure water. The underlying mechanism of wavelength-dependent N-2 fixation in the presence of surface defects is proposed, with an emphasis on oxygen vacancies that not only facilitate the activation and dissociation of N-2 but also improve light absorption and the separation of the photoexcited carriers. Both NH4+ and NO3(-)can be produced in pure water under a simulated solar light and even till the wavelength reaching 730 nm. The maximum quantum efficiency reaches 9% at 365 nm. Theoretical calculation reveals that disproportionation reaction of the N-2 molecule is more energetically favorable than either reduction or oxidation alone. It is worth noting that the molar fraction of NH4+ in the total product (NH4+ plus NO3-) shows an inverted volcano shape from 365 nm to 730 nm. The increased fraction of NO3-. from 365 nm to around 427 nm results from the competition between the oxygen evolution reaction (OER) at W sites without oxygen vacancies and the N-2 oxidation reaction (NOR) at oxygen vacancy sites, which is driven by the intrinsically delocalized photoexcited holes. From 427 nm to 730 nm, NOR is energetically restricted due to its higher equilibrium potential than that of OER, accompanied by the localized photoexcited holes on oxygen vacancies. Full disproportionation of N-2 is achieved within a range of wavelength from similar to 427 nm to similar to 515 nm. This work presents a rational strategy to efficiently utilize the photoexcited carriers and optimize the photocatalyst for practical nitrogen fixation.

ESCI ; EI

英语

其他

National Key R&D Program of China[2016YFB0700600] ; Guangdong Innovation Team Project[2013N080] ; Soft Science Research Project of Guangdong Province[2017B030301013] ; Shenzhen Science and Technology Research Grant[ZDSYS201707281026184] ; Shenzhen Peacock Plan[KQTD2014062714543296]

Science & Technology - Other Topics

Multidisciplinary Sciences

WOS:000537415800001

AMER ASSOC ADVANCEMENT SCIENCE

20202908949350

Nitrogen fixation ; Nitrates ; Oxidation ; Ammonia ; Light absorption ; Energy efficiency ; Surface defects

Energy Conservation:525.2 ; Light/Optics:741.1 ; Chemical Reactions:802.2 ; Inorganic Compounds:804.2 ; Crystalline Solids:933.1 ; Materials Science:951

Web of Science

1.Peking Univ, Sch Adv Mat, Shenzhen Grad Sch, Beijing, Peoples R China
2.Chongqing Univ Posts & Telecommun, Sch Adv Mfg Engn, Chongqing, Peoples R China
3.Southern Univ Sci & Technol, Dept Mat Sci & Engn, Shenzhen, Peoples R China
4.Southern Univ Sci & Technol, SUSTech Acad Adv Interdisciplinary Studies, Shenzhen, Peoples R China
5.Chinese Acad Sci, Inst Chem, Beijing, Peoples R China

Ren, Wenju,Mei, Zongwei,Zheng, Shisheng,et al. Wavelength-Dependent Solar N-2 Fixation into Ammonia and Nitrate in Pure Water[J]. Research,2020,2020.

Ren, Wenju.,Mei, Zongwei.,Zheng, Shisheng.,Li, Shunning.,Zhu, Yuanmin.,...&Pan, Feng.(2020).Wavelength-Dependent Solar N-2 Fixation into Ammonia and Nitrate in Pure Water.Research,2020.

Ren, Wenju,et al."Wavelength-Dependent Solar N-2 Fixation into Ammonia and Nitrate in Pure Water".Research 2020(2020).