Optimized the Carrier Transport Path and Separation Efficiency of 2D/2D Heterojunction in Photoelectrochemical Water Splitting

Abstract

It is a promising strategy that the photoelectrode with high charge transfer rate and separation efficiency is designed in the photoelectrochemical (PEC) water splitting. Herein, the nanoflakes/nanoflakes (2D/2D) MoS 2 /ZnIn 2 S 4 heterojunction is synthesized by two-step hydrothermal methods. The carrier transport path in heterojunction is optimized through the Schottky contact calculated by density functional theory (DFT) and large specific surface area between 2D nanoflakes MoS 2 and ZnIn 2 S 4 . Besides, the bimetallic oxyhydroxide NiFeOOH can be used as co-catalyst to improve the separation of carriers. The results exhibit that MoS 2 /ZnIn 2 S 4 /NiFeOOH photoelectrode with dramatically enhanced photocurrent density of 0.74 mA/cm 2 at 1.23 V versus the reversible hydrogen electrode (V RHE ), which is 2.6 and 5.7 times higher than the bare MoS 2 and ZnIn 2 S 4 , respectively. And it has the largest charge separation efficiency (η bulk ) (22.8 %) and charge transfer efficiency (η surface ) (64.6 %) in the as-prepared samples. This work provides a strategy for design of the photoelectrode with excellent charge transfer efficiency and separation efficiency in PEC water splitting.

Bundle-Type Columnar Cu2O Photoabsorbers with Vertical Grain Boundaries Fabricated Using Instant Strike-Processed Metallic Seeds and Their Enhanced Photoelectrochemical Efficiency

“…The next step illustrates the relevance between the bundle-type columnar structures with vertical grain boundaries and the transport/transfer efficiencies. The measured overall photocurrent ( J PEC ) for PEC operation can be expressed as where J abs , η tp , and η tr corresponds to the estimated values of light absorbance, charge transport efficiency, and charge transfer efficiency, respectively. − As shown in Figure S8, the optical absorbance spectra for samples C0 and C001 exhibit no meaningful differences. Further, their expected photocurrents ( J abs ) are revealed to be almost the same, 10.8 and 10.7 mA cm –2 at 0 V RHE , where J abs values are calculated using the following equations where P 0 is the power provided by a solar simulator (with AM 1.5 G filter), A is the measured absorbance, and P abs is the power of light actually absorbed by the photoelectrode .…”

Cu-Ion-Implanted and Polymeric Carbon Nitride-Decorated TiO2 Nanotube Array for Unassisted Photoelectrochemical Water Splitting

“…Photoelectrochemical (PEC) water splitting, an artificial photosynthesis process, has been considered as a green and sustainable strategy for hydrogen production because it can directly convert the inexhaustible and clean solar energy into storable and transportable hydrogen gas. , Generally, the overall PEC water splitting is composed of two half-reactions: (1) the hydrogen evolution reaction (HER) and (2) the oxygen evolution reaction (OER). Compared with the former, the PEC-OER is usually accompanied by sluggish kinetics because it involves a 4e – transfer process with multiple intermediates, which limits the rate and the efficiency of the whole PEC water splitting .…”

“…Photoelectrochemical (PEC) water splitting, an artificial photosynthesis process, has been considered as a green and sustainable strategy for hydrogen production because it can directly convert the inexhaustible and clean solar energy into storable and transportable hydrogen gas. 6,7 Generally, the overall PEC water splitting is composed of two half-reactions:…”