N,P-codoped porous carbon derived from chitosan with hierarchical N-enriched structure and ultra-high specific surface Area toward high-performance supercapacitors

In this work,a facile"carbonization-activation"strategy is developed to synthesize N,P-codoped hierarchical porous carbon.Phosphoric acid is innovatively introduced during the hydrothermal process to achieve in-situ P doping as well as create abundant pores,and the employment of sodamide is of vital importance to simultaneously serve as activating agent and N-source to succeed a high-level N doping.Thus,the obtained samples exhibit a unique three-dimensional hierarchical structure with an ultra-high specific surface area(3646 m^(2)g^(-1))and ultra-high N-doping level(9.81 at.%).Computational analyses confirm that N,P co-doping and higher N content can enhance active sites and widen potential differences of carbon materials to improve their capacitance.The as-prepared carbon materials demonstrate superior electrochemical performances,such as an ultra-high capacitance of 586 Fg^(-1)at 1 Ag^(-1),a superior rate capability of 409 Fg^(-1)at 20 Ag^(-1),and excellent long-term stability of 97%capacitance retention after10,000 cycles in 6 M KOH.Moreover,an assembled symmetric supercapacitor delivers a high energy density of 28.1 Wh kg^(-1)at the power density of 450 W kg^(-1)in 1 M Na_(2)SO_(4),demonstrating a great potential for applications in supercapacitors.

A widely adaptable approach to generate integration-free iPSCs from non-invasively acquired human somatic cells

Dear Editor Human pluripotent stem cells including human embryonic stem cells （ESCs） and induced pluripotent stem cells （iPSCs） are cells displaying abilities of unlimited self-renewal and differentiation into any somatic cell type. These unique properties make them increasingly attractive for novel applications in disease modeling, drug discovery, and cell therapy （Buganim et al., 2014; Liu et al., 2011; Liu et al., 2012; Sanchez Alvarado and Yamanaka, 2014）. Moreover, iPSCs hold great potential for personalized cell therapy as they avoid some of the ethical concerns as well as the immunological rejection issues ascribed to ESCs.