Graphitic carbon nitride (g‐C3N4)‐based nanosized heteroarrays: Promising materials for photoelectrochemical water splitting

Liqun Wang,Feng Hou,Yueyu Tong,Thomas Lippert,Jungang Hou,Daniele Pergolesi,Wenping Si,Ji Liang,Shi Xue Dou

doi:10.1002/cey2.48

Abstract

AbstractPhotoelectrochemical (PEC) water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source, utilization of inexhaustible solar energy, high‐purity product, and environment‐friendly process. To actualize a practical PEC water splitting, it is paramount to develop efficient, stable, safe, and low‐cost photoelectrode materials. Recently, graphitic carbon nitride (g‐C3N4) has aroused a great interest in the new generation photoelectrode materials because of its unique features, such as suitable band structure for water splitting, a certain range of visible light absorption, nontoxicity, and good stability. Some inherent defects of g‐C3N4, however, seriously impair further improvement on PEC performance, including low electronic conductivity, high recombination rate of photogenerated charges, and limited visible light absorption at long wavelength range. Construction of g‐C3N4‐based nanosized heteroarrays as photoelectrodes has been regarded as a promising strategy to circumvent these inherent limitations and achieve the high‐performance PEC water splitting due to the accelerated exciton separation and the reduced combination of photogenerated electrons/holes. Herein, we summarize in detail the latest progress of g‐C3N4‐based nanosized heteroarrays in PEC water‐splitting photoelectrodes. Firstly, the unique advantages of this type of photoelectrodes, including the highly ordered nanoarray architectures and the heterojunctions, are highlighted. Then, different g‐C3N4‐based nanosized heteroarrays are comprehensively discussed, in terms of their fabrication methods, PEC capacities, and mechanisms, etc. To conclude, the key challenges and possible solutions for future development on g‐C3N4‐based nanosized heteroarray photoelectrodes are discussed.

Highlights

The so‐called “hydrogen energy” refers to the chemical energy stored in hydrogen fuel, which can be released and further converted to electricity through hydrogen fuel cells to power a range of equipment, such as the hydrogen fuel cell vehicles
Apart from these, the hydrogen gas obtained from this route always has CO impurity, which is very poisonous for many catalysts and hard to be completely removed, making such hydrogen fuel very unsuitable to be directly used in hydrogen fuel cells.[21]
All of the results clearly show that the ultrathin graphitic carbon nitride (g‐C3N4) NSs can serve as excellent cocatalyst for Bi2MoO6 array to enhance the PEC performance

Summary

Introduction

Due to the excessive dependence on traditional fossil fuels, such as coal, oil, and natural gas, our society has been facing with a series of severe crises: energy shortage, environmental pollution, and global warming.[1,2,3] A practical solution for these issues is to harvest and utilize clean and renewable energies to replace the aforementioned fossil fuels.[4,5] Up to now, more and more types of green energy have been gradually developed and utilized, including solar energy,[6,7,8,9,10] wind energy,[11] wave energy,[12] biomass energy,[13] hydrogen energy,[14,15] etc.

Results

Conclusion