Benign-by-design N-doped carbonaceous materials obtained from the hydrothermal carbonization of sewage sludge for supercapacitor applications

This contribution discloses a new methodology for the preparation of N-doped carbon via the hydrothermal carbonization (HTC) of sewage sludge (SS). The aqueous phase served as the nitrogen source as it contained a large number of soluble proteins and cellulose, and rice husk served as the sugar source. The results showed that the lignin in the rice husk interfered with the hydrolysis of cellulose and hemicellulose. In comparison, the particle size of N-hydrochar produced from the co-HTC of cellulose and the aqueous phase of SS was uniform. Remarkably, the resulting carbon materials exhibited a maximum specific capacitance of 286.68 F g-1 at a current density of 1 A g-1 and also retained 76.74% of the capacitance at an ultrahigh current density of 20 A g-1. A maximum energy density of 39.81 W h kg-1 was obtained. Moreover, 97.55% of the initial capacitance of the assembled supercapacitor can be maintained after 10 000 cycles, exhibiting long cycling stability. The present method provides a new approach towards the preparation of sustainable functional carbon materials for energy applications from wastewater formed via HTC of SS. © The Royal Society of Chemistry.

Xu Z.-X.1 , Deng X.-Q.1 , Zhang S. 2 , Shen Y.-F.3 , Shan Y.-Q.4 , Zhang Z.-M.5 , Luque R. 6, 7 , Luque R. 6, 7 , Duan P.-G.4 , Hu X.5
Royal Society of Chemistry
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  • 1 School of Energy and Power Engineering, Jiangsu University, Zhenjiang, 212013, China
  • 2 College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, 210037, China
  • 3 School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, China
  • 4 Shaanxi Key Laboratory of Energy Chemical Process Intensification, School of Chemical Engineering and Technology, Xi'An Jiaotong University, No. 28 West Xianning Road, Xi'an, Shaanxi, 710049, China
  • 5 School Materials Science and Engineering, University of Jinan, Jinan, 250022, China
  • 6 Departamento de Quimica Organica, Campus de Rabanales Edificio Marie Curie (C-3), Ctra Nnal IV-A Km 396, Cordoba, E14014, Spain
  • 7 Peoples Friendship University of Russia, RUDN University, 6 Miklukho-Maklaya str., Moscow, 117198, Russian Federation
Capacitance; Carbon; Carbonization; Cellulose; Particle size; Sewage sludge; Supercapacitor; Thermochemistry; Carbonaceous materials; Cellulose and hemicellulose; Cycling stability; Energy applications; Hydrothermal carbonization; Soluble proteins; Specific capacitance; Supercapacitor application; Doping (additives); Capacitance; Carbonization; Cellulose; Particle Size; Thermochemistry
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