Challenges and Opportunities in Electrocatalytic CO2 Reduction to Chemicals and Fuels.

The global temperature increase must be limited to below 1.5 °C to alleviate the worst effects of climate change. Electrocatalytic CO2 reduction (ECO2 R) to generate chemicals and feedstocks is considered one of the most promising technologies to cut CO2 emission at an industrial level. However, despite decades of studies, advances at the laboratory scale have not yet led to high industrial deployment rates. This Review discusses practical challenges in the industrial chain that hamper the scaling-up deployment of the ECO2 R technology. Faradaic efficiencies (FEs) of about 100 % and current densities above 200 mA cm-2 have been achieved for the ECO2 R to CO/HCOOH, and the stability of the electrolysis system has been prolonged to 2000 h. For ECO2 R to C2 H4 , the maximum FE is over 80 %, and the highest current density has reached the A cm-2 level. Thus, it is believed that ECO2 R may have reached the stage for scale-up. We aim to provide insights that can accelerate the development of the ECO2 R technology.

Infrared photodetector based on GeTe nanofilms with high performance.

GeTe is an important narrow band gap semiconductor material, which has found application in the fields of thermoelectricity, phase change storage as well as switch. However, it has not been studied for application in the field of photodetectors. Here, GeTe thin films were grown by magnetron sputtering and their material structure, optical and electrical properties were compared before and after annealing. High-performance photodetectors with detectivity of ${\sim}{{10}^{13}}$∼1013 Jones at 850 nm light were demonstrated. Thus the novel, to the best of our knowledge, application of GeTe in optoelectronic devices is reported in this work.

Highly responsive MoS2 photodetectors enhanced by graphene quantum dots.

Molybdenum disulphide (MoS2), which is a typical semiconductor from the family of layered transition metal dichalcogenides (TMDs), is an attractive material for optoelectronic and photodetection applications because of its tunable bandgap and high quantum luminescence efficiency. Although a high photoresponsivity of 880-2000 AW(-1) and photogain up to 5000 have been demonstrated in MoS2-based photodetectors, the light absorption and gain mechanisms are two fundamental issues preventing these materials from further improvement. In addition, it is still debated whether monolayer or multilayer MoS2 could deliver better performance. Here, we demonstrate a photoresponsivity of approximately 10(4) AW(-1) and a photogain of approximately 10(7) electrons per photon in an n-n heterostructure photodetector that consists of a multilayer MoS2 thin film covered with a thin layer of graphene quantum dots (GQDs). The enhanced light-matter interaction results from effective charge transfer and the re-absorption of photons, leading to enhanced light absorption and the creation of electron-hole pairs. It is feasible to scale up the device and obtain a fast response, thus making it one step closer to practical applications.