Defect Engineering in Photocatalytic Methane Conversion

Abstract

With the rapid increase in the discovered reserves of methane, tremendous efforts have been devoted to the conversion of methane into value‐added chemicals. However, current methane conversion technologies require extensive energy consumption (i.e., high temperature and pressure) due to the high stability of methane molecules. Recently, photocatalytic methane conversion has emerged as a potential answer for the above limitation because it can produce reactive intermediates for C—H bond activation by utilizing solar energy as the sole energy input and allow the methane conversion to proceed under mild conditions. Yet, its conversion efficiency remains relatively low mainly due to scarce active sites and rapid photogenerated charge carrier recombination. In this regard, defect engineering, which can create enormous active sites for methane activation and modulate the electronic structure of photocatalyst, has been extensively utilized for photocatalytic methane conversion. In this review, the fundamentals and advantages of various defects along with their preparation strategies are first summarized. Then, recent advances in defect‐mediated photocatalytic methane conversion are highlighted. Finally, the challenges and opportunities on defect‐mediated photocatalytic methane conversion are presented. This review is expected to provide a timely overview of the state‐of‐the‐art development of the defect‐mediated photocatalytic methane conversion toward its practical application.

Recent research progress on operational stability of metal oxide/sulfide photoanodes in photoelectrochemical cells

“…Although the loading of the OECs and passivation layer improves the stability of the photoanode, introducing interfacial defects in the process of supporting the OECs often worsens the photoanode stability [89,90]. To address the interfacial defects between the OECs and photoanode interface, researchers usually support the OECs by in situ techniques or by introducing an interfacial layer [91,92].…”

Integrating Covalent Organic Framework with Transition Metal Phosphide for Noble‐Metal‐Free Visible‐Light‐Driven Photocatalytic H2 Evolution

“…However, in comparison with lactic acid, the L‐ascorbic acid can be oxidized more effectively because of a lower oxidation potential. [ 4–45 ] Therefore, in this work, the L‐ascorbic acid was chosen as the sacrificial agent in the following tests.…”

“…In recent years, sunlight-driven H 2 production has received tremendous interest and is considered one of the most promising technologies for converting and storing light energy to green fuels. [1][2][3][4][5][6][7][8][9] Thus, investigating highly effective and stable photocatalysts appears to be greatly crucial. As a kind of emerging crystalline porous materials, 2D covalentorganic frameworks (COFs), constructed through condensation of molecular building blocks, have been widely studied in gas adsorption/separation, chemical sensing, electrochemistry, ionic conduction, etc.…”

Harnessing the Defects at Hetero‐Interface of Transition Metal Compounds for Advanced Charge Storage: A Review

“…Oxygen vacancies and other nonmetal vacancies often exist at the hetero-interface between TMCs, resulting in the misdistribution of carriers, which can accelerate ion conduction and enhance electrochemical performance. [113][114][115][116] In addition, the band structure change caused by elemental doping can create a built-in electric field at the TMC hetero-interface and improve the electrochemical process. [117][118][119] 1D linear defects in heterostructures generally consist of edge dislocations, helical dislocations, and phase interfaces (lateral hetero-interfaces), which usually occur on the 2D layers.…”