Photoelectrochemical Activity of Ag Coated 2D‐TiO₂/RGO Heterojunction for Hydrogen Evolution Reaction and Environmental Remediation

Abstract

Intermittent nature of renewable energy led us more to incline over energy conversion and storage. Thus, use of solar radiation towards energy conversion e. g. hydrogen evolution, environmental‐remediation etc. are emerging areas where the materials should be capable of absorbing light energy and transform this absorbed energy into other application. In the present work, the photoelectrochemical and photocatalytic activity of the Ag/TiO2 /RGO catalyst for hydrogen evolution reaction (HER) and methyl orange dye degradation has been reported. Ag/TiO2 /RGO catalyst showed the highest current density for HER which was ca. 2 and 3 times more than Ag NPs and TiO2 nanoflakes, respectively. The interfacial charge transfer between RGO‐TiO2‐Ag hetero‐junction actually improves the charge separation and increases both the photocatalytic activity and hydrogen generation. The composite was also equally capable to degrade environmental pollutant and with the addition of silver, methyl orange dye degradation percentage enhances from 8.9 % (TiO2 nanoflakes) to 81 % (for Ag/TiO2/RGO) with the increment in rate constant from 9.38 X 10−4 (TiO2 nanoflakes) to 1.69×10−2 min−1.

Photoelectrochemical Degradation of Organic Pollutants Coupled with Molecular Hydrogen Generation Using Bi2O3/TiO2 Nanoparticle Arrays

“…The overlay of core-level O 1s spectra is plotted in Figure c. Two peaks in Ti 2p spectra (Figure d) at 458.7 and 464.4 eV in the case of TNRs are assigned to Ti 2p 3/2 and Ti 2p 1/2 , respectively, where the intense peaks are attributed to Ti 4+ and a small concentration of Ti 3+ in comparison to Ti 4+ is also observed. The O 1s spectra for 20-BTRs and NTRs are shown in Figure e, and the XPS peak can be deconvoluted in two peaks corresponding to lattice oxygen and surface hydroxyl groups .…”

“…Among all the semiconducting materials, modified TiO 2 particularly is being utilized for photoelectrocatalytic degradation of pollutant molecules due to its high number of catalytic active sites, a deep positive valence band edge, and an excellent chemical stability in a large window of potential bias and pH. 17,18 Additional advantages of TiO 2 are its low toxicity, abundance, and inexpensive price. 19,20 1-D nanorods of TiO 2 have several advantages over other TiO 2 morphologies (such as films, nanoparticles, and nanotube arrays) for energy and environmental applications because of their high aspect ratio and high specific surface area.…”

“…19,20 1-D nanorods of TiO 2 have several advantages over other TiO 2 morphologies (such as films, nanoparticles, and nanotube arrays) for energy and environmental applications because of their high aspect ratio and high specific surface area. 19,21 TiO 2 has been utilized to construct photoelectrodes for PEC treatment of organic pollutants and a heavy metal co-contamination system; 18,22 but its wide band gap, which could only be excited by UV light, restricts its application. 23 Considering that visible light occupies about 43% of sunlight reaching the earth surface, expanding the response of TiO 2 from UV to the visible region by compounding with narrow band gap semiconductors has been studied intensively.…”

“…The performance of a good photoelectrocatalyst depends upon the nature of photoelectrode materials used. Among all the semiconducting materials, modified TiO 2 particularly is being utilized for photoelectrocatalytic degradation of pollutant molecules due to its high number of catalytic active sites, a deep positive valence band edge, and an excellent chemical stability in a large window of potential bias and pH. , Additional advantages of TiO 2 are its low toxicity, abundance, and inexpensive price. , 1-D nanorods of TiO 2 have several advantages over other TiO 2 morphologies (such as films, nanoparticles, and nanotube arrays) for energy and environmental applications because of their high aspect ratio and high specific surface area. , TiO 2 has been utilized to construct photoelectrodes for PEC treatment of organic pollutants and a heavy metal co-contamination system; , but its wide band gap, which could only be excited by UV light, restricts its application . Considering that visible light occupies about 43% of sunlight reaching the earth surface, expanding the response of TiO 2 from UV to the visible region by compounding with narrow band gap semiconductors has been studied intensively. , For example, TiO 2 has been modified with CdS, , BiOI, , MoS 2 , , g-C 3 N 4 , , Bi 2 O 3 , , Fe 2 O 3 , etc.…”