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Band Gap Engineering in an Efficient Solar-Driven Interfacial Evaporation System
journal contribution
posted on 2020-07-09, 19:36 authored by Peijin Ying, Meng Li, Feilin Yu, Yang Geng, Liyang Zhang, Junjie He, Yujie Zheng, Rong ChenSolar-driven
interfacial evaporation system is attracting intensive
attention for harvesting clean water in the utilization of solar energy.
To improve solar-driven interfacial evaporation performance for better
application, structuring a solar absorber with high solar–thermal
conversion efficiency is critical. Semiconductor materials with stable
and economic properties are good candidates as solar absorbers. Semiconductors
with a narrow band gap have been proved to offer a broad solar absorption
spectrum in the applications of photoelectricity and photocatalysis.
However, the correlation between band gap and solar-driven interfacial
evaporation performance has not been systematically studied. Herein,
TiO2 is selected as a semiconductive absorber and a reproducible
process is developed to fabricate band gap engineered TiO2 to understand the relationship between the “electronic structure”
and the “performance” in the field of solar-driven interfacial
evaporation. After the band gap engineering from 3.2 to 2.23 eV, correlative
tests of solar-driven interfacial evaporation performance as well
as first-principles calculations are employed to study the correlation
mentioned above. As a result, we find that a narrower band gap contributes
to improved solar–thermal conversion efficiency and the Ti3+-doped TiO2 (Ti3+-TiO2)
with the narrowest band gap of 2.23 eV outperforms other samples,
achieving the highest evaporation rate of 1.20 kg m–2 h–1 (solar–thermal conversion efficiency
of 77.1%). Besides, the Ti3+-TiO2 also shows
the good ability of photocatalytic degradation. This work may provide
a way for semiconductor materials to be designed as solar absorbers
with higher solar–thermal conversion efficiency and better
solar-driven interfacial evaporation performance for applications
in clean water harvesting.