Dan Yang,Lei Zhao,Xueting Feng,Lili Ma,Hanming Ding
As a potential nonmetal activator of peroxymonosulfate (PMS), g -C 3 N 4 becomes a hot material owing to its superior chemical and physical properties. Nevertheless, pristine g -C 3 N 4 is unsatisfactory for PMS activation because of its limited photo-generated charge separation and low specific surface area. Herein, a porous sulfur-doped g -C 3 N 4 (S-doped g -C 3 N 4 ) has been prepared through a one-step calcination route without a template. The in - situ doping of sulfur element and the formation of porous morphology have been confirmed via various characterization methods. The catalytic activity of porous S-doped g -C 3 N 4 is approximately 6.2-fold higher than that of the pristine g -C 3 N 4 on rhodamine B (RhB) decomposition in aid of the photo-assisted PMS activation. The superior catalytic activity and high stability of the porous S-doped g -C 3 N 4 catalyst in a wide pH range are attributed to its higher specific surface area, enriched active sites, efficient photo-induced charge separation, and increased visible-light utilization. Meantime, a synergistic effect between the PMS activation process and the photocatalytic process is conducive to produce abundant radicals for the RhB degradation. This study offers new insight into further developing highly efficient nonmetal heterogeneous catalysts for wastewater treatment.
Simultaneously achieving a high conductivity and a good volume-change accommodation for sulfur cathode in lithium‑sulfur batteries is highly required. Herein, we present a unique porous sulfur composite consisting of a porous sulfur particle coating with conductive hydrogel polypyrrole , which is prepared through a templated method. The pores inside the sulfur particles offer a good buffering space for the volume expansion of sulfur upon lithiation; while the external polypyrrole coating improves the conductivity and suppress the transfer of polysulfides . The porous sulfur@polypyrrole composite exhibits a capacity of about 900 mAh g −1 after cycling for 100 times at 0.12 C, along with a good Coulombic efficiency around 99.9%, which is much better than the polypyrrole-coated non-porous sulfur particles and pure sulfur particles. When cycled for 500 times, the capacity fading rate is as low as 0.09% per cycle. After three rounds of rate-performance measurements, the capacity retention of the sulfur@polypyrrole at different rates remain above 97%. The density functional theory calculations and electrochemical impedance spectra demonstrate a polysulfide-adsorptive and a stable electric transportation surface of the sulfur@polypyrrole composite, respectively.
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