Rationally Designed n–n Heterojunction with Highly Efficient Solar Hydrogen Evolution

Abstract

In most of the reported n-n heterojunction photocatalysts, both the conduction and valence bands of one semiconductor are more negative than those of the other semiconductor. In this work, we designed and synthesized a novel n-n heterojunction photocatalyst, namely CdS-ZnWO4 heterojunctions, in which ZnWO4 has more negative conduction band and more positive valence band than those of CdS. The hydrogen evolution rate of CdS-30 mol %-ZnWO4 reaches 31.46 mmol h(-1) g(-1) under visible light, which is approximately 8 and 755 times higher than that of pure CdS and ZnWO4 under similar conditions, respectively. The location of the surface active sites is researched and a plausible mechanism of performance enhancement by the tuning of the structure is proposed based on the photoelectrochemical characterization. The results illustrate that this kind of nonconventional n-n heterojunctions is also suitable and highly efficient for solar hydrogen evolution.

Graphene-wrapped Ag 3 PO 4 /LaCO 3 OH heterostructures for water purification under visible light

“…This process continues until the equilibrium is attained (Equalized Fermi level Ef) with generation of build in electric field directed from LCO to APO [41]. When heterojunction is illuminated by solar light (Figure 10b), the generated built-in field promotes the formation of photogenerated charge carriers in APO, which will flow the electrons towards LCO [41].…”

Fe2O3–TiO2nanosystems by a hybrid PE-CVD/ALD approach: controllable synthesis, growth mechanism, and photocatalytic properties

“…30,[32][33][34] Nevertheless, it tends to have short carrier diffusion lengths and facility to recombine electron-hole pairs, being thus ineffective in driving photocatalytic reactions. 4,37 So far, both iron-doped TiO 2 9,17,18,20,23,38 and mixed Fe-Ti oxides 2,7,10,16,24,36 have been used in a variety of photocatalytic degradation processes not only in the liquid phase, 2,7,16,18,19,22,28,38 but also in the gas phase. In particular, the development of Fe 2 O 3 -TiO 2 nanostructures offers, in principle, a possible solution for the production of photocatalysts with improved charge transport properties and functional performances, 2,20,36 even upon solar/vis illumination.…”

Synthesis of novel Ag/Ag2O heterostructures with solar full spectrum (UV, visible and near-infrared) light-driven photocatalytic activity and enhanced photoelectrochemical performance

“…Fig. S9 [23]. The photocatalytic mechanism is proposed for the observed UV, visible and NIR photocatalytic activity of Mott-Schottky-type Ag/Ag 2 O heterostructures (Fig.…”