Photocatalytic overall water splitting by graphitic carbon nitride

Abstract

Photocatalytic overall water splitting (OWS) without using any sacrificial reagent to realize H2 and O2 production in the stoichiometric ratio of 2:1 is viewed as the “holy grail” in the field of solar fuel production. Developing stable, low cost, and nontoxic photocatalysts that have satisfactory solar‐to‐hydrogen conversion efficiency is of significance but challenging for realizing the large‐scale use of this sustainable technology. Among various photocatalysts, graphitic carbon nitride (GCN) has shown great potential as an ideal candidate to fulfill the breakthrough in this dynamic research field due to its attractive physicochemical properties. Herein, for the first time, the state‐of‐the‐art research progress of GCN for photocatalytic OWS is reviewed. We first summarize the basic principle of photocatalytic OWS along with the advantages/challenges of GCN introduced. The strategies that have been used to modulate the OWS activity of GCN are then reviewed, including cocatalyst investigation, morphology modulation, atomic structure modification, crystallinity engineering, and heterostructure construction. Toward the end of the review, the concluding remarks and perspectives for the future development are presented, with our expectation to provide some new ideas for the design of advanced OWS photocatalysts.

Advances in metal-based vanadate compound photocatalysts: synthesis, properties and applications

“…Therefore, it provides very powerful oxidation and reduction ability. Another study found that 3D g-C3N4 showed increased exciton resolution, better mobility and separation of charge carriers than g-C3N4 nanosheets, which implies the way for more electron transport in 3D morphology [60]. In particular, g-C3N4 nanosheets had a notably reduction in activity (less than 44%) because of the accumulation of nanosheets, while 3D g-C3N4 did not show significant inactivation, which confirms its high stability for the overall water splitting reaction [61].…”

“…One of the most important fuels is hydrogen, which is a promising and renewable chemical fuel due to its high energy density and environmentally friendly [99]. Clean generation of H2 by water splitting using a semiconductor photocatalyst and solar energy, without relying on fossil reserves, is a new technology [60] which is a target pursued by chemists over the past decade. Half of the solar energy at the earth surface is in the visible region (400<λ<800 nm), so the efficient use of visible light is essential to achieve large-scale practical H2 production by photocatalytic water splitting [100].…”

Transition‐Metal‐Based Cocatalysts for Photocatalytic Water Splitting

“…In the long term, it is not practical for large‐scale production of solar fuels, especially in the cases where the cost of sacrificial agents is even higher than produced energy itself, and the conversion products of some sacrificial agents maybe cause environmental problems. [ 413 ] Therefore, photocatalytic overall water splitting is particularly desirable. In the photocatalytic overall water splitting process, the high overpotential and activation energy as well as sluggish kinetics especially for the O 2 evolution half‐reaction enable it to be dynamically difficult to proceed.…”

Tailor‐Engineered 2D Cocatalysts: Harnessing Electron–Hole Redox Center of 2D g‐C3N4 Photocatalysts toward Solar‐to‐Chemical Conversion and Environmental Purification

“…[ 9 ] As such, photocatalyst must possess an appropriate electronic band structure and superior light absorption coefficient to maximize the harvesting and utilization of solar photons. [ 10 ] Intrinsically, appreciable amount of photoinduced electrons and holes will migrate to the surface of photocatalyst to undergo redox reactions. [ 11 ] Moreover, the energetic level of band structure needs to straddle the redox potential of the desired reactions, thus fulfilling the requirement of both thermodynamics and kinetics for highly efficient photocatalytic reactions.…”