Insights into the efficient charge separation and transfer efficiency of La,Cr-codoped SrTiO3 modified with CoP as a noble-metal-free co-catalyst for superior visible-light driven photocatalytic hydrogen generation†
Abstract
The exploration of non-noble-metal-based photocatalysts with high efficiency and durability toward hydrogen evolution is vitally necessary to meet the challenges of the global energy and environmental crisis. In this work, we prepared noble-metal-free cobalt phosphide (CoP) as an efficient co-catalyst on La,Cr-codoped SrTiO3 (La,Cr:SrTiO3) to form a novel photocatalyst with enhanced H2 evolution activity. It was evidenced that the introduction of CoP led to a remarkable improvement in the photocatalytic H2 evolution activity of La,Cr:SrTiO3, and the content of CoP in the composite had an important influence on the photocatalytic activity. The optimized La,Cr:SrTiO3/CoP (4 wt%) composite exhibited a catalytic H2 evolution rate of 198.4 μmol h−1 g−1, which was nearly 27 and 15 times higher than that of La,Cr:SrTiO3 and CoP, even slightly higher than that of La,Cr:SrTiO3/Pt (0.5 wt%). More importantly, this novel photocatalyst also showed a long-term stability without noticeable activity degradation. Based on the results of UV–vis diffuse reflectance spectroscopy, photoluminescence spectra, photocurrent response, and electrochemical impedance spectra, we ascribed the enhanced H2 evolution performance of the La,Cr:SrTiO3/CoP to a synergistic effect including the broadened visible-light response range, accelerated photogenerated charge separation and transfer efficiency. It is believed that our present work throws light on the rational design of novel, high-performance, visible-light-driven hybrid photocatalysts based on non-noble-metal elements.