Heteroatom Nitrogen- and Boron-Doping as a Facile Strategy to Improve Photocatalytic Activity of Standalone Reduced Graphene Oxide in Hydrogen Evolution

Owing to its superior properties and versatility, graphene has been proliferating the energy research scene in the past decade. In this contribution, nitrogen (N-) and boron (B-) doped reduced graphene oxide (rGO) variants were investigated as a sole photocatalyst for the green production of H₂ and their properties with respect to photocatalysis were elucidated for the first time. N- and B-rGOs were facilely prepared via the pyrolysis of graphene oxide with urea and boron anhydride as their respective dopant source. The pyrolysis temperature was varied (600–800 °C for N-rGO and 800–1000 °C for B-rGO) in order to modify dopant loading percentage (%) which was found to be influential to photocatalytic activity. N-rGO600 (8.26 N at%) and B-rGO1000 (3.59 B at%), which holds the highest at% from each of their party, exhibited the highest H₂ activity. Additionally, the effects of the nature of N and B bonding configuration in H₂ photoactivity were also examined. This study demonstrates the importance of dopant atoms in graphene, rendering doping as an effective strategy to bolster photocatalytic activity for standalone graphene derivative photocatalysts

Self-Assembled Heteroepitaxial AuNPs/SrTiO₃: Influence of AuNPs Size on SrTiO₃ Band Gap Tuning for Visible Light-Driven Photocatalyst

Self-assembled heteroepitaxial offers tremendous opportunity to tailor optical and charge transport properties in noble metal–semiconductor interface. Here, we incorporated gold nanoparticles (AuNPs) onto the {001} facets of semiconductor strontium titanate, SrTiO₃ (STO), by means of heteroepitaxial approach to investigate the band gap tuning and its effect of photoresponse. We demonstrate that the Fermi energy level of the system can be tuned by controlling the AuNPs size. X-ray photoelectron spectroscopy (XPS) shows that the energy difference between Sr_3d and Au_4f core levels measured in the AuNPs/STO (100) heterojunction increases from 47.90 to 49.26 eV with decreasing AuNPs size from 65 to 16 nm, respectively. Hence, the Fermi energy level was shifted toward the conductive band of STO (100), and the system charge transfer efficiency was improved. It was also found that smaller AuNPs sizes exhibited a higher photoactivity as the result of the band gap narrowing effect. Photoactivity was improved by broadening the catalyst absorption spectrum to the visible light region. This study provides a basic understanding of the photoelectrochemistry of metal–semiconductor heterostructure for visible light-energy conversion

Tuning Electronic Transport in a Self-Assembled Nanocomposite

Self-assembled nanocomposites with a high interface-to-volume ratio offer an opportunity to overcome limitations in current technology, where intriguing transport behaviors can be tailored by the choice of proper interactions of constituents. Here we integrated metallic perovskite oxide SrRuO₃–wurzite semiconductor ZnO nanocomposites to investigate the room-temperature metal–insulator transition and its effect on photoresponse. We demonstrate that the band structure at the interface can be tuned by controlling the interface-to-volume ratio of the nanocomposites. Photoinduced carrier injection driven by visible light was detected across the nanocomposites. This work shows the charge interaction of the vertically integrated multiheterostructures by incorporating a controllable interface-to-volume ratio, which is essential for optimization of the design and functionality of electronic devices