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Defect-minimized directly grown graphene-based solar cells

Cui Yiqian, Wei Jiaqi, Jia Lizhe, Zhang Lukai, Zhou Qing, Liu Yanliang, Zhang Yong, Zhang Yu, Yu Wei

Materials Science Poland

2022

Vol. 40, No. 3

125--134

Using plasma-enhanced chemical vapor deposition (PECVD) to directly grow graphene nanowalls (GNWs) on silicon to preparate the solar cells is compatible with current industrial production. However, many defects in the GNWs hinder improvement of the power conversion efficiency (PCE) of solar cells. In this work, we found that the defects in GNWs can be reduced under the condition of keeping the appropriate sheet resistance of GNWs by simultaneously reducing the growth temperature and increasing the growth time. Then, a PCE of 3.83% was achieved by minimizing the defects in the GNWs under the condition of ensuring adequate coverage of GNWs on bare planar silicon. The defects in GNWs were further reduced by adding a poly(3,4-ethylenedioxythiophene) (PEDOT):Nafion passivation coating, and the PCE was significantly improved to10.55%. Our work provides an innovative path and a simple approach to minimize the defects in graphene grown directly on silicon for high-efficiency solar cells.

Effect of swelling clay dispersion type on fine coal flotation

Zhang Mingqing, Yu Wei, Cao Yijun, Xu Haiyu

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 2

380--388

The influence of bentonite dispersion on fine coal flotation was examined to better understand the role of swelling clay in the process of flotation. It was found that the coal flotation recovery was lower with uncontrolled dispersion of bentonite than with controlled dispersion. The detrimental effect was attributed to the increase in slime coating. In the uncontrolled dispersion, the dispersed bentonite platelets formed an extensive card-house structure. The three-dimensional networks increased the slurry viscosity, and caused significant coating of the coal particles, thereby inhibiting particle mobility and bubble-particle attachment. In the controlled dispersion, the bentonite mineral appeared as separate particles with low aspect ratios. The coal particles were partially coated, and the slurry viscosity was lower, resulting in higher flotation recovery. The findings in this study suggested that a practical solution to mitigate the negative impact of swelling clay on flotation would be to maintain high electrolyte levels in the wash water to inhibit clay swelling and dispersion.

Environmental Regulation and Employment: Evaluating the Role of Water Pollution Prevention and Control Law in China

Yu Wei, Liu Xiao

Problemy Ekorozwoju

2018

Vol. 13, nr 2

7--16

In this paper, we investigate the impact of environmental regulations on employment in China. We apply a quasi-natural experiment on the revision of Water Pollution Prevention and Control Law in 2008 (WPPCL2008), and we analyze manufacturing sectors’ reaction to WPPCL2008 by using a differences-in-differences approach based on China’s thirty five sectors at the 2-digit level from 2003 to 2014. Our results show that although environmental regulations can reduce waste-water emissions, at the same time cause a decrease in employment. The results suggest that stringent environmental regulation is not cost free. Furthermore, this finding contradicts the popular view that the effect of Chinese legislation enforcement is insignificant.

W tym artykule analizujemy wpływ środowiskowych regulacji prawnych na zatrudnienie w Chinach. Przygotowaliśmy eksperyment odnoszący się do poprawionej Ustawy o zapobieganiu zanieczyszczeniom wody i kontroli jakości wód z 2008 r. (WPPCL2008) i przeanalizowaliśmy reakcję na zmienione prawo ze strony sektora produkcyjnego korzystając z metody DID (differences-in-differences), uwzględniając 35 sektorów występujących w Chinach i 2-cyfowy poziom pomiędzy 2003 a 2014 r. Otrzymane rezultaty pokazują, że surowe regulacje środowiskowej nie są wolne od kosztów. Co więcej, okazuje się, że są one sprzeczne z poglądem, że chińskie prawodawstwo jest nieistotne.