Toward Ultrathin: Advances in Solution-Processed Organic Semiconductor Transistors
Gang Zhou, Yun Shan, Longlu Wang, Youyou Hu,
发布时间：xxxx-xx-xx
10, Article number: 399 (2019)
Abstract
The exploitation of the stable and earth-abundant electrocatalyst with high catalytic activity remains a significant challenge for hydrogen evolution reaction. Being different from complex nanostructuring, this work focuses on a simple and feasible way to improve hydrogen evolution reaction performance via manipulation of intrinsic physical properties of the material. Herein, we present an interesting semiconductor-metal transition in ultrathin troilite FeS nanosheets triggered by near infrared radiation at near room temperature for the first time. The photogenerated metal-phase FeS nanosheets demonstrate intrinsically high catalytic activity and fast carrier transfer for hydrogen evolution reaction, leading to an overpotential of 142 mV at 10 mA cm−2 and a lower Tafel slope of 36.9 mV per decade. Our findings provide new inspirations for the steering of electron transfer and designing new-type catalysts.
Humankind has relied on fossil fuel in the past decades, causing significant degradation of global environment and frequent extreme weather. To solve this problem, huge efforts have been made to develop efficient and accessible energy conversion technologies in an attempt to produce sustainable and renewable energy sources1,2,3,4. Electrocatalytic water splitting for hydrogen evolution reaction (HER) is usually considered to be a promising and practical option because hydrogen can work as a versatile energy carrier, but is facing the dilemma of low conversion efficiency and high cost5,6,7. A grand challenge is the lack of inexpensive and excellent electrocatalysts with low overpotential and a small Tafel slope to drive hydrogen evolution7,8,9. So far, many earth-abundant materials such as transition metal dichalcogenides, sulfides, nitrides, and phosphides have been proposed to replace the costly Pt-based catalysts10,11,12,13,14,15,16. To achieve excellent HER performance, most research attentions have been directed toward preparation strategies, e.g., constructing various nanostructures6,13 and introducing vacancies9 or dopants2,5. It is generally known that a promising catalyst should possess high activity (appropriate Gibbs free energy), large number of exposed active sites (large superficial area), and low resistance for carrier transfer (good metal properties)11,17,18. These key elements strongly depend on the material’s intrinsic physical properties. In principle, the design of excellent catalysts should be proceeded from the regulation of material’s essence, such as structural phase transition10,19,20,21. If a semiconductor–metal transition is realized at near-room temperature via light exposure, the catalytic activity and carrier transfer will be efficiently regulated in a simple way.
Herein, we report the highly efficient hydrogen evolution triggered by photoinduced semiconductor–metal transition at near-room temperature for the first time. This phase transition occurs in ultrathin troilite FeS nanosheets vertically grown on carbon fiber cloth (CFC). The inexpensive troilite FeS material is chosen as the candidate since previous reports have confirmed that a semiconductor–metal transition easily occurs in FeS bulk material at ~400 K22,23,24. Our work witnesses the ultrathin FeS nanosheets with more active sites that have obviously enhanced the response to near-infrared (NIR) radiation, which can impel more light-excited carriers to join into the phase transition process and drastically lower the transition temperature near room temperature. The photogenerated metal-phase FeS nanosheets exhibit enhanced carrier transfer and higher catalytic activity, which is about eight times higher in HER performance than the semiconductor phase.