S-Scheme Heterojunction/Single-Atom Dual-Driven Charge Transport for Photocatalytic Hydrogen Production

Abstract

The rational design and modification of heterojunction photocatalysts aimed at achieving fast charge transport and efficient photocatalytic performance is a central goal of solar-lightdriven water splitting and hydrogen evolution, yet this remains a challenge. Herein, we prepare a hierarchical photocatalyst composed of a few-layer violet phosphorene (VP), cadmium sulfide (CdS) nanoparticles (NPs), and Pd single atoms (SAs) by a facile one-step ball-milling strategy. The underlying VP/CdS p−n heterojunctions are verified to adopt S-scheme directional charge transfer by combining in situ irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance. The atomically dispersed Pd sites of the low-valence state coupled with the VP/CdS S-scheme heterojunctions synergistically achieve ultrafast electron transport (2.2 ps), in which the interfacial Pd−S and Pd−P bonds serve as electron transfer channels. In addition, density-functional theory calculations reveal the key role of Pd atoms in the enhancement of light-harvesting capacity and optimization of proton adsorption thermodynamics. A visible-light hydrogen production rate of 82.5 mmol h −1 g −1 is attained by an optimal 1 wt % Pd−5 wt % VP/ CdS photocatalyst, which manifests a 54-fold increase with respect to that of CdS NPs, in addition to an apparent quantum efficiency (AQE) of 25.7% at 420 nm. This work showcases a valid combination of S-scheme heterojunctions and SAs for efficient charge separation promoting photocatalytic hydrogen evolution, and others.

Progress of Covalent Organic Framework Photocatalysts: From Crystallinity–Stability Dilemma to Photocatalytic Performance Improvement

“…Among a wide range of photoactive materials, metal oxides, − metal sulfides, − and conjugated polymers, − are the most broadly studied photocatalysts where prototype ones are TiO 2 , CdS, and g-C 3 N 4 . However, each prototype photocatalyst holds inherent drawbacks.…”

Heterostructured Photocatalysts for Water Splitting and the Interfacial Charge Transfer

“…At the full spectrum, the Z-Scheme charge transfer path has the stability of thermodynamically driven overall water splitting (Figure c). Utilizing one-step ball-milling method, Li et al synthesized a hierarchical photocatalyst comprising a multilayered structure of violet phosphorene (VP) nanosheets, CdS nanoparticles (NPs), and Pd single atoms (SAs) . The in situ XPS and electron paramagnetic resonance verified that VP/CdS p–n heterojunction shows S-Scheme charge transfer as shown in Figure d.…”