Oriented Built-in Electric Field Introduced by Surface Gradient Diffusion Doping for Enhanced Photocatalytic H₂ Evolution in CdS Nanorods

Abstract

Element doping has been extensively attempted to develop visible-light-driven photocatalysts, which introduces impurity levels and enhances light absorption. However, the dopants can also become recombination centers for photogenerated electrons and holes. To address the recombination challenge, we report a gradient phosphorus-doped CdS (CdS-P) homojunction nanostructure, creating an oriented built-in electric-field for efficient extraction of carriers from inside to surface of the photocatalyst. The apparent quantum efficiency (AQY) based on the cocatalyst-free photocatalyst is up to 8.2% at 420 nm while the H evolution rate boosts to 194.3 μmol·h·mg, which is 58.3 times higher than that of pristine CdS. This concept of oriented built-in electric field introduced by surface gradient diffusion doping should provide a new approach to design other types of semiconductor photocatalysts for efficient solar-to-chemical conversion.

Enabling Visible‐Light‐Driven Selective CO2 Reduction by Doping Quantum Dots: Trapping Electrons and Suppressing H2 Evolution

“…Both pristine CdS QDs and Ni:CdS QDs exhibit photoluminescence (PL) around 600 nm (Figure 3a). [10,11,14] Here,N i doping can enhance the PL around 600 nm ( Figure S8), as more photoexcited electrons are transferred to the surface This argument is supported by the PL spectra collected in the presence of methyl viologen (MV 2+ ), an agent to sacrifice surface electrons of QDs,w hich display aw eak emission peak for radiative recombination in the bulk at 500-550 nm (Figure 3b).…”

“…[10,11,14] In ap ractical photocatalytic CO 2 reduction, the photoexcited electrons trapped at surface Ni sites would participate in reactions with Ni atoms as the catalytic centers. [10,11,14] In ap ractical photocatalytic CO 2 reduction, the photoexcited electrons trapped at surface Ni sites would participate in reactions with Ni atoms as the catalytic centers.…”

Gradient Energy Band Driven High‐Performance Self‐Powered Perovskite/CdS Photodetector

“…In spite of great progresses, it is complicated to fabricate composite electronic transport layers (ETLs) with matched crystal lattices and energy levels, otherwise the newly formed interface in the composite may bring about large amounts of defects which act as trap sites and recombination centers.Spatially graded composition (bandgap) is an effective route to continuously tune energy levels and bandgap in semiconductors, [20,21] in which the interfacial recombination is alleviated or removed and a graded built-in potential through the whole bulk is produced, enabling stronger separation capability of photogenerated electron-hole pairs. In spite of great progresses, it is complicated to fabricate composite electronic transport layers (ETLs) with matched crystal lattices and energy levels, otherwise the newly formed interface in the composite may bring about large amounts of defects which act as trap sites and recombination centers.…”

“…Spatially graded composition (bandgap) is an effective route to continuously tune energy levels and bandgap in semiconductors, [20,21] in which the interfacial recombination is alleviated or removed and a graded built-in potential through the whole bulk is produced, enabling stronger separation capability of photogenerated electron-hole pairs. This concept provides a new platform for designing high-performance optoelectronic devices.…”

Structure and Band Alignment Engineering of CdS/TiO2/Bi2WO6 Trilayer Nanoflake Array for Efficient Photoelectrochemical Water Splitting

“…[6][7][8][9] The PEC application of CdS has been intensively studied. [20] Numerous modification methods have been employed to enhance the PEC activity and stability of CdS photoanode, including morphology manipulation, [23][24][25] doping [15,26] and heterojunction construction. Moreover, CdS suffers from serious photocorrosion under illumination because the photogenerated holes induce the self-oxidization of S 2À .…”