A perspective on possible amendments in semiconductors for enhanced photocatalytic hydrogen generation by water splitting

Ishaq, Tehmeena; Yousaf, Maryam; Bhatti, Ijaz Ahmad; Batool, Aisha; Asghar, Muhammad Adeel; Mohsin, Muhammad; Ahmad, Muhammad

doi:10.1016/j.ijhydene.2021.09.165

Cited by 53 publications

(15 citation statements)

References 128 publications

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“…However, it requires energy to split water. Depending on the power source, water splitting can be categorized into three groups: (i) thermochemical water splitting, (ii) photobiological water splitting, and (iii) photocatalytic water splitting [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

et al. 2023

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Nanomaterials have attracted attention for application in photocatalytic hydrogen production because of their beneficial properties such as high specific surface area, attractive morphology, and high light absorption. Furthermore, hydrogen is a clean and green source of energy that may help to resolve the existing energy crisis and increasing environmental pollution caused by the consumption of fossil fuels. Among various hydrogen production methods, photocatalytic water splitting is most significant because it utilizes solar light, a freely available energy source throughout the world, activated via semiconductor nanomaterial catalysts. Various types of photocatalysts are developed for this purpose, including carbon-based and transition-metal-based photocatalysts, and each has its advantages and disadvantages. The present review highlights the basic principle of water splitting and various techniques such as the thermochemical process, electrocatalytic process, and direct solar water splitting to enhance hydrogen production. Moreover, modification strategies such as band gap engineering, semiconductor alloys, and multiphoton photocatalysts have been reviewed. Furthermore, the Z- and S-schemes of heterojunction photocatalysts for water splitting were also reviewed. Ultimately, the strategies for developing efficient, practical, highly efficient, and novel visible-light-harvesting photocatalysts will be discussed, in addition to the challenges that are involved. This review can provide researchers with a reference for the current state of affairs, and may motivate them to develop new materials for hydrogen generation.

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Section: Introductionmentioning

confidence: 99%

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

et al. 2023

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“…Nowadays, there are harsh requirements on pollutant emission lowering with simultaneous depletion of fossil fuels and the growth of energy demand implementation of alternative energy sources, and development of new efficient eco-friendly technologies has become one of the target challenges of scientific society. In this respect, photocatalytic and electrocatalytic overall water splitting seems to be the desired alternative, attracting considerable researcher’s attention. − However, the slow kinetics of the water oxidation, oxygen evolution reaction (OER), as well as the low durability of obtained catalysts limits the efficiency and, as a result, prevents the large-scale application of this process. The development of new, highly efficient, and stable OER catalysts, therefore, becomes the key goal in this direction.…”

Section: Introductionmentioning

confidence: 99%

“…It is interesting to note that appearance of a very close absorption band after the addition of sodium periodate is also observed for parent Ir_ANC solutions. Therefore, the noted intense transfer of the Ir into the solution during the functioning of the Ir/g-C 3 N 4 catalysts can be attributed (1) to the generation of reactive oxygen species at the active centers of catalysts, causing the dissolution of iridium and (2) a strong complexing ability of the periodate and iodate anions toward transition metal cations that additionally facilitates the leaching. The leached Ir species remains active in the OER, which is confirmed by the difference of reaction curves for experiments with and without washing of the catalysts.…”

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Highly Active Visible Light-Promoted Ir/g-C₃N₄ Photocatalysts for the Water Oxidation Reaction Prepared from a Halogen-Free Iridium Precursor

Topchiyan

Vasilchenko

Ткачев

et al. 2022

ACS Appl. Mater. Interfaces

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A combination of the exceptional stability of fac-[Ir(H2O)3(NO2)3] together with thermolability of nitro and aqua ligands and high solubility in various solvents makes it promising as a brand-new chlorine-free precursor of iridium for the preparation of heterogeneous catalysts. In the current work, a new technique of fac-[Ir(H2O)3(NO2)3] preparation based on hydrothermal treatment of (NH4)3[Ir(NO2)6] was developed. For this purpose, the influence of reaction parameters such as the reaction time, temperature, and pH of the solution on the process of hexanitroiridate salt hydrolysis was investigated. The synthesized fac-[Ir(H2O)3(NO2)3] solution in this optimized way was used for the preparation of the series of Ir/g-C3N4 catalysts, which were evaluated in the water oxidation reaction with NaIO4 utilized as a sacrificial reagent. A 20-fold enhancement of the oxygen evolution reaction (OER) activity was found to take place under visible light (λ = 411 nm) illumination of the systems. The highest rate of the photoinduced OER per iridium center was achieved by the Ir0.005/g-C3N4 (air, 400°C) catalyst with an exceptional turnover frequency value of 967 min–1 approaching the activity of known homogeneous iridium OER catalysts. The leaching experiments have shown that aquated Ir species are generated in a solution after prolonged functioning of the catalysts. Despite this, in the closed system the photodriven OER activity persists at a steady-state level evidencing an equilibrium achieved between dissolved and anchored Ir species forming catalytic tandem with the g-C3N4.

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“…Advanced oxidation processes (AOPs) are one of the appropriate technologies for removal of pollutants from effluent, and photocatalytic removal of heavy metals is very fast as compared to other AOPs ( Iqbal and Bhatti, 2015 ; Jamal et al, 2015 ; Wu et al, 2020 ; Ishaq et al, 2021 ). So far, setup for the reduction of heavy metals and decomposition of organic pollutants using optimized combinations of oxidants, catalyst loading time, and irradiation time have been developed.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Solar Photocatalytic Activity of Thermally Stable I:ZnO/Glass Beads for Reduction of Cr(VI) in Tannery Effluent

et al. 2022

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Chromium (VI) in tannery effluent is one of the major environmental concerns for the environmentalists due to the hazardous nature of Cr(VI) ions. To reduce Cr(VI) to Cr(III) as an innocuous moiety, pure and I-doped ZnO was grafted over the etched surface of glass beads by successive ionic layer adsorption and reaction (SILAR). Powdered, pure, and I-doped ZnO scrapped from the surface of glass beads was characterized for crystallinity, morphology, and elemental composition by XRD, SEM, TEM, and EDX. The optical properties of both photocatalysts revealed that owing to optimized iodine doping of ZnO, reduction in the bandgap was observed from 3.3 to 2.9 eV. The crystalline nano-bricks of I:ZnO adhered to glass beads were investigated to have remarkable capability to harvest sunlight in comparison to intrinsic ZnO nanodiscs. The thermal stability of I:ZnO was also found to be much improved due to doping of ZnO. The photocatalytic activities of ZnO/GB and I:ZnO/GB were compared by extent of reduction of Cr(VI) under direct natural sunlight (600–650 KWh/m2). The disappearance of absorbance peaks associated with Cr(VI) after treatment with I:ZnO/GB confirmed higher photocatalytic activity of I:ZnO/GB. The reaction parameters of solar photocatalytic reduction, i.e., initial pH (5–9), initial concentration of Cr(VI) (10–50 ppm), and solar irradiation time (1–5 h) were optimized using response surface methodology. The solar photocatalytic reduction of Cr(VI) to Cr(III) present in real tannery effluent was examined to be 87 and 98%, respectively, by employing ZnO/GB and I:ZnO/GB as solar photocatalysts. The extent of reduction was also confirmed by complexation of Cr(VI) and Cr(III) present in treated and untreated tannery waste with 1, 5-diphenylcarbazide. The results of AAS and UV/vis spectroscopy for the decrease in concentration of Cr also supported the evidence of higher efficiency of I:ZnO/GB for reduction of Cr(VI) in tannery effluent. Reusability of the fabricated photocatalyst was assessed for eight cycles, and magnificent extent of reduction of Cr(VI) indicated its high efficiency. Conclusively, I:ZnO/GB is a potential and cost-effective candidate for Cr(VI) reduction in tannery effluent under natural sunlight.

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A perspective on possible amendments in semiconductors for enhanced photocatalytic hydrogen generation by water splitting

Cited by 53 publications

References 128 publications

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

Highly Active Visible Light-Promoted Ir/g-C₃N₄ Photocatalysts for the Water Oxidation Reaction Prepared from a Halogen-Free Iridium Precursor

Enhanced Solar Photocatalytic Activity of Thermally Stable I:ZnO/Glass Beads for Reduction of Cr(VI) in Tannery Effluent

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A perspective on possible amendments in semiconductors for enhanced photocatalytic hydrogen generation by water splitting

Cited by 53 publications

References 128 publications

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

Semiconductor Nanomaterial Photocatalysts for Water-Splitting Hydrogen Production: The Holy Grail of Converting Solar Energy to Fuel

Highly Active Visible Light-Promoted Ir/g-C3N4 Photocatalysts for the Water Oxidation Reaction Prepared from a Halogen-Free Iridium Precursor

Enhanced Solar Photocatalytic Activity of Thermally Stable I:ZnO/Glass Beads for Reduction of Cr(VI) in Tannery Effluent

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Highly Active Visible Light-Promoted Ir/g-C₃N₄ Photocatalysts for the Water Oxidation Reaction Prepared from a Halogen-Free Iridium Precursor