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

Abstract

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.

Colloidal semiconductor nanocrystals: from bottom-up nanoarchitectonics to energy harvesting applications

“…177 The basic principles of solar water splitting and carbon dioxide reduction (COOR) are available in recent reviews. [353][354][355][356][357] Photocatalysts that can achieve overall water splitting and COOR activity must meet three requirements: (a) light absorption to generate electron-hole pairs, (b) matching of the band structure with the redox potentials of water splitting, and (c) effective separation of photoexcited carriers to trigger redox reactions (Fig. 9a).…”

“…23,360 Semiconductor photocatalysts are often loaded with metallic cocatalysts, which presumably promotes the charge separation of photogenerated electrons and holes and acted as the site for hydrogen generation. 22,118,177,257,356 Amirav et al reported multicomponent heterostructure NCs composed of a platinum-tipped CdSe-CdS nanorods, which exhibited the efficient photocatalytic production of hydrogen (Fig. 9b).…”

Surface sensitization of g-C3N4/TiO2via Pd/Rb2O co-catalysts: accelerating water splitting reaction for green fuel production in the absence of organic sacrificial agents

“…5 These pressing issues need to be resolved by developing effective and resilient technologies. 6 The only favorable method that can deal with the current environmental issues is utilizing solar energy instead of fossil fuels. 7 Sunlight is a clean, secure, non-polluting and limitless energy source.…”

V2O5–Fe3O4/rGO Ternary Nanocomposite with Dual Applications as a Dye Degradation Photocatalyst and OER Electrocatalyst

“…On the other hand, growing concerns about environmental contamination resulting from the massive consumption of nonrenewable resources such as fossil fuels have prompted the global community to investigate green and renewable energy sources. One promising approach for generating clean energy is via the electrocatalytic splitting of water using semiconductor catalysts, which has the potential to provide a sustainable source of oxygen and hydrogen. , To electrolyze water, two distinct electrochemical half-cell reactions, the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), are required. In an electrochemical process, the reaction overpotential can be quantified by measuring the potential required to achieve a specific current density, and it is characterized as the deviation between the actual potential and the theoretical equilibrium potential for an electrode.…”