Contact-electro-catalysis for Direct Synthesis of H2 O2 under Ambient Conditions.

Hydrogen peroxide (H2 O2 ) is an indispensable basic reagent in various industries, such as textile bleach, chemical synthesis, and environmental protection. However, it is challenging to prepare H2 O2 in a green, safe, simple and efficient way under ambient conditions. Here, we found that H2 O2 could be synthesized using a catalytic pathway only by contact charging a two-phase interface at room temperature and normal pressure. Particularly, under the action of mechanical force, electron transfer occurs during physical contact between polytetrafluoroethylene particles and deionized water/O2 interfaces, inducing the generation of reactive free radicals (⋅OH and ⋅O2 - ), and the free radicals could react to form H2 O2 , yielding as high as 313 µmol L-1 h-1 . In addition, the new reaction device could show long-term stable H2 O2 production. This work provides a novel method for the efficient preparation of H2 O2 , which may also stimulate further explorations on contact-electrification-induced chemistry process.

Promotion Strategies of Hole Transport Materials by Electronic and Steric Controls for n-i-p Perovskite Solar Cells.

Hole transport materials (HTMs) play a requisite role in n-i-p perovskite solar cells (PSCs). The properties of HTMs, such as hole extraction efficiency, chemical compatibility, film morphology, ion migration barrier, and so on, significantly affect PSCs' power conversion efficiencies (PCEs) and stabilities. Up till now, researchers have devoted much attention to developing new types of HTMs as well as promoting pristine HTMs using numerous strategies. In this Review, we summarize the design strategies of various common HTMs for n-i-p PSCs are comprehensively discussed from two separate aspects (additive and non-additive engineering). Additive engineering generally tunes electronic properties of HTMs while non-additive engineering basically modifies their steric structures. Critical analysis and comparison between these design strategies are provided, considering the overall PCEs and stabilities of PSCs. Finally, a brief perspective on future promising design strategies for HTMs is given, in order to fabricate efficient and stable n-i-p devices for the commercialization of PSCs.