Polysulfide shuttle effect and sluggish sulfur reaction kinetics severely impede the cycling stability and sulfur utilization of lithium-sulfur (Li-S) batteries. Modulating d-band electronic structures of molybdenum disulfide electrocatalysts via p/n doping is promising to boost polysulfide conversion and suppress polysulfide migration in lithium-sulfur batteries. Herein, p-type V-doped MoS 2 (V-MoS 2 ) and n-type Mn-doped MoS 2 (Mn-MoS 2 ) catalysts are well-designed. Experimental results and theoretical analyses reveal that both of them significantly increase the binding energy of polysulfides on the catalysts’ surface and accelerate the sluggish conversion kinetics of sulfur species. Particularly, the p-type V-MoS 2 catalyst exhibits a more obvious bidirectional catalytic effect. Electronic structure analysis further demonstrates that the superior anchoring and electrocatalytic activities are originated from the upward shift of the d-band center and the optimized electronic structure induced by duplex metal coupling. As a result, the Li-S batteries with V-MoS 2 modified separator exhibit a high initial capacity of 1607.2 mAh g −1 at 0.2 C and excellent rate and cycling performance. Moreover, even at a high sulfur loading of 6.84 mg cm −2 , a favorable initial areal capacity of 8.98 mAh cm −2 is achieved at 0.1 C. This work may bring widespread attention to atomic engineering in catalyst design for high-performance Li-S batteries.
Hong-Rui Zhu,Xi-Lun Wang,Juan-Juan Zhao,Meng-Han Yin,Hui-Min Xu,Gao-Ren Li
Plastics are ubiquitous in human life and pose certain hazards to the environment and human body. The increasing amount of CO 2 in the atmosphere will lead to the greenhouse effect. Therefore, it is urgent to treat microplastic waste and CO 2 by using environmentally friendly and efficient technologies. In this work, we developed an efficient photoelectrocatalytic system composed of Ni single atoms (Ni SAs) supported by P, N-doped amorphous NiFe 2 O 4 (Ni SAs/A-P-N-NFO) as anode and Ag nanoparticles (Ag NPs) supported by CuO/Cu 2 O nanocubes (Ag NPs@CuO/Cu 2 O NCs) as cathode for microplastic oxidation and CO 2 reduction. The Ni SAs/A-P-N-NFO was synthesized by calcination-H 2 reduction method, and it achieved a Faraday efficiency of 93% for the oxidation reaction of poly (ethylene terephthalate) (PET) solution under AM 1.5 G light. As a photocathode, the synthesized Ag NPs@CuO/Cu 2 O NCs was utilized to reduce CO 2 to ethylene and CO at 1.5 V vs . RHE with selectivity of 42% and 55%, respectively. This work shows that the photoelectrocatalysis, as an environmentally friendly technology, is a feasible strategy for reducing the environmental and biological hazards of light plastics, as well as for efficient CO 2 reduction.
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