Pt Particle Size Affects Both the Charge Separation and Water Reduction Efficiencies of CdS–Pt Nanorod Photocatalysts for Light Driven H₂ Generation

Abstract

Decreasing the metal catalyst size into nanoclusters or even single atom is an emerging direction of developing more efficient and cost-effective photocatalytic systems. Because the catalyst particle size affects both the catalyst activity and light driven charge separation efficiency, their effects on the overall photocatalytic efficiency are still poorly understood. Herein, using a well-defined semiconductor–metal heterostructure with Pt nanoparticle catalysts selectively grown on the apexes of CdS nanorods (NRs), we study the effect of the Pt catalyst size on light driven H2 generation quantum efficiency (QEH2 ). With the increase of the Pt catalyst size from 0.7 ± 0.3 to 3.0 ± 0.8 nm, the QEH2 of CdS–Pt increases from 0.5 ± 0.2% to 38.3 ± 5.1%, by nearly 2 orders of magnitude. Transient absorption spectroscopy measurement reveals that the electron transfer rate from the CdS NR to the Pt tip increases with the Pt diameter following a scaling law of d 5.6, giving rise to the increase of electron transfer efficiency at larger Pt sizes. The observed trend can be understood by a simplified kinetic model that assumes the overall efficiency is the product of the quantum efficiencies of charge separation (including hole transfer, electron transfer, and hole scavenging) and water reduction steps, and for CdS–Pt NRs, the quantum efficiencies of electron transfer and water reduction steps increase with the Pt sizes. Our findings suggest the importance of improving the quantum efficiencies of both charge separation and catalysis in designing efficient semiconductor–metal hybrid photocatalysts, especially in the regime of small metal particle sizes.

Trash to Treasure: Photoreforming of Plastic Waste into Commodity Chemicals and Hydrogen over MoS2-Tipped CdS Nanorods

“…As shown in Figure g, the profile of the Mo element is completely focused on the end of CdS, which is a sign of the selective growth of MoS 2 on the end of CdS nanorods. Such a heterostructure based on metallic domains tipped with one-dimensional (1D) semiconductors contributes to the rapid transfer and separation efficiency of charge carriers via spatially localized deeper energy states. − …”

Ternary Dumbbell Nanowires for Photocatalytic Hydrogen Production

“…Indeed, in the most fundamental hybrid system, the semiconductor photocatalyst is loaded with cocatalysts that promote charge separation and lower the activation potential for hydrogen evolution, thus greatly enhancing the photocatalytic activity. , In addition to proper cocatalyst selection, its location on the photocatalytic system, the number of cocatalyst domains, , and the catalyst shape , and size − were all found to influence the performance of the hybrid system. Hence, great care should be devoted for precise control over these parameters.…”

Regulating Encapsulation of Small Pt Nanoparticles inside Silicalite-1 Zeolite with the Aid of Sodium Ions for Enhancing n-Hexane Reforming

“…The size of metal particles is one of the key factors in determining the performance of the reforming of straight-chain alkanes. Generally, metal clusters or/and single atoms have better catalytic properties than metal particles due to the exposure of more accessible active sites and improvement of the charge transfer between metal and support and/or other metals. − Among these catalysts, Pt supported on chlorine-containing alumina (Pt/Al 2 O 3 –Cl) is the common commercial catalyst for naphtha reforming and it is efficient for the transformation of C 8 and higher alkanes to aromatics. ,− However, it is hard to convert C 6 or C 7 alkane over Pt/Al 2 O 3 –Cl. Moreover, Pt/Al 2 O 3 –Cl belongs to a metal-acid bifunctional catalyst, which is prone to bring about some side reactions such as isomerization and cracking over the acid sites, thus resulting in low aromatics selectivity. − In addition, the reforming process of n-alkanes is thermodynamically limited and highly endothermic, so a high reaction temperature is required to reach a reasonable conversion.…”