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United States Energy Foundation project [G-1111-15134]; Ministry of Education, Philosophy and Social Planning project [12YJAZH056]; China Postdoctoral Science Foundation [20090460202]; National Natural Science Foundation of China [710201139]; Fundamental Research Funds for the Central Universities [2010221040]; National Bureau of Statistics Funds from China [2011LD002]

The rational design and synthesis of environmental, low-cost and eco-friendly renewable biomass-based carbons are highly desired for the development of high-performance supercapacitors. Herein, a novel amide-enriched synthesis strategy for biomass-based carbon from bayberry core (BC) by in-situ melamine-BC prepolymerization and subsequent NH3 ammonization. The synthesized biomass-based BC carbons were characterized by N2adsorption/desorption, scanning electron microscope, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results showed that the BC carbons by melamine and ammonization co-treatment had both much higher N-doping level (up to 6.43%) and surface area (up to 960 m2 g−1) than the N-free doped carbon. The doped N functional group was mainly dominated by the form of amide-N rather than pyridine-N or quaternary-N. More excitingly, the amide-N content increased with the extension of ammonization time while pyridine-N and quaternary-N went down. The prepared amide-enriched BC carbon via 20 g melamine pre-polymerization and 3 h ammonization treatment delivered an excellent specific capacitance of 259 F g−1, which was 35–72 F g−1 higher than the samples by 1h and 2h NH3 treatment though the latter two had much higher surface area, pyridine and quaternary-N content. The results indicated that the amide-N on the N-doped biomass-based carbon made a great role for enhancing the capacitance, and its promotion to electric double layer capacitance and pseudo-capacitance exceeded that of pyridine and quaternary-N.

Researchers have been driven to investigate sustainable alternatives to cement production, such as geopolymers, due to the impact of global warming and climate change resulting from greenhouse gas emissions. Currently, they are exploring different methods and waste materials to enhance the mechanical and physical properties of geopolymer and expand its application range. This review paper offers a thorough analysis of the utilization of various waste materials in geopolymer manufacturing and shows the creative contribution of this research to the development of environmentally friendly cement substitutes. The article covers the properties, durability, and practical applications of geopolymer composites made from various waste binders. It includes a microstructure and chemical analysis. The research findings indicate that geopolymers are an effective cementitious binder substitute for cement in various applications. Additionally, the ecological and carbon footprint analysis highlights the sustainability of geopolymers compared to cement.

The vertical multi-junction (VMJ) solar cell has good potential applications in high concentration photovoltaic. The efficiency of VMJ cell reached to 19.19% under 2480 suns has been reported. Numerical calculations show that the efficiency can reach close to 30% after optimization. In this work, the performance of the silicon VMJ cell with front surface diffusion working under 1 sun and 1000 suns was calculated numerically using a TCAD software. The front surface diffusion can reduce the requirement of high quality front surface passivation, but increases the series resistance. The effect of the N-type emitter dopant profile, P+-type back surface field dopant profile, width, thickness, bulk doping concentration and lifetime of the sub-cell on the performance of the VMJ cell with front surface diffusion was calculated and analyzed. The efficiency reached to 30.56% under 1000 suns after optimization.

European physical journal special topics 228(2), 261-623 (2019). doi:10.1140/epjst/e2019-900045-4 Published by Springer, Berlin ; Heidelberg