Wenjie Wang

Bio: Wenjie Wang is an academic researcher from Fudan University. The author has contributed to research in topics: Graphyne. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Mechanochemical constructing ordered rhombic channels in graphyne analogues for rapid potassium-ion storage

Abstract: Constructing a new topological structure with unique ordered channels for rapid potassiation kinetics is crucial to ameliorating the inherent drawbacks of carbon anodes, arising from the large K-ion radius, such as huge volume expansion, slow diffusion rate, and poor interfacial transfer dynamics. Herein, dihydrogen- and nitrogen/hydrogen-substituted rhombic graphynes (HH-rGY, NH-rGY) were synthesized through a mechanochemical cross-coupling method using specific D2h-symmetric tetrahalogenated organic molecules and alkynyl-containing calcium carbide as precursors. The pyridinic-N atoms in NH-rGY can efficiently manipulate electron distribution and tailor structural arrangement, endowing unique AA'-stacking mode with ordered vertical rhombic channels, board interlayer spacing of 4.1 A (1.16 times to that of HH-rGY), and negligible volumetric expansion (< 3%) during potassiation, which are investigated by experiments and theoretical calculations. Instead of a common capacitive-dominated storage mechanism, intercalation-dominated K-storage is verified in rhombic graphynes by quantitative kinetics analysis. Especially, the NH-rGY electrode delivers a reversible capacity of 230 mAh g-1 at 50 mA g-1 (90.2% after 500 cycles) and 97 mAh g-1 at 5 A g-1 and retains 146 mAh g-1 at 2 A g-1 after 5000 cycles, owing to outstanding structural stability and rapid in-plane and inter-layer K+ diffusion. This work proposes a universal mechanochemical cross-coupling synthetic methodology and brings new insight into the topological structure design of carbon skeletons for high-performance potassium storage.

Bias-free synthesis of hydrogen peroxide from photo-driven oxygen reduction reaction using N-doped γ-graphyne catalyst

Abstract: It is an ideal route to generate hydrogen peroxide (H2O2) via selective 2e- ORR powered directly by sunlight. In this work, we synthesized a metal-free N-doped γ-graphyne catalyst and wired it with n-type semiconductor photoanodes. The introduction of sunlight could lower the onset bias of oxygen reduction reaction (ORR) up to 0.32 V and H2O2 was steadily produced without any sacrificial agents and bias. The 2e- ORR selectivity of N-doped γ-graphyne catalyst was bias dependent, and it reached about 74% at 0 bias in 0.1 mol·L−1 KOH. Theoretical calculations showed that in-situ pyridinic-N in N-doped γ-graphyne acted as the active site for ORR, accelerating the rate-determining step of proton abstraction. The H2O2 yield reached as high as 7.47 mmol·h−1g−1, outperformed the reported traditional photocatalytic syntheses of H2O2.

Bias-free synthesis of hydrogen peroxide from photo-driven oxygen reduction reaction using N-doped γ-graphyne catalyst

Abstract: It is an ideal route to generate hydrogen peroxide (H2O2) via selective 2e- ORR powered directly by sunlight. In this work, we synthesized a metal-free N doped γ-graphyne catalyst and wired it with n-type semiconductor photoanodes. The introduction of sunlight could lower the onset bias of oxygen reduction reaction (ORR) up to 0.32 V and H2O2 was steadily produced without any sacrificial agents and bias. The 2e- ORR selectivity of N doped γ-graphyne catalyst was bias dependent, and it reached about 74% at 0 bias in 0.1 mol·L-1 KOH. Theoretical calculations showed that in-situ pyridinic-N in N doped γ-graphyne acted as the active site for ORR, accelerating the rate-determining step of proton abstraction. The H2O2 yield reached as high as 7.47 mmol·h-1g-1, outperformed the reported traditional photocatalytic syntheses of H2O2.