Geometric and Electronic Engineering in Co/VN Nanoparticles to Boost Bifunctional Oxygen Electrocatalysis for Aqueous/Flexible Zn-Air Batteries.

Modulating metal-metal and metal-support interactions is one of the potent tools for augmenting catalytic performance. Herein, highly active Co/VN nanoparticles are well dispersed on three-dimensional porous carbon nanofoam (Co/VN@NC) with the assistance of dicyandiamide. Studies certify that the consequential disordered carbon substrate reinforces the confinement of electrons, while the coupling of diverse components optimizes charge redistribution among species. Besides, theoretical analyses confirm that the regulated electron configuration can significantly tune the binding strength between the active sites and intermediates, thus optimizing reaction energy barriers. Therefore, Co/VN@NC exhibits a competitive potential difference (ΔE, 0.65 V) between the half-wave potential of ORR and OER potential at 10 mA cm-2, outperforming Pt/C+RuO2 (0.67 V). Further, catalyst-based aqueous/flexible ZABs present superior performances with peak power densities of 156 and 85 mW cm-2, superior to Pt/C-based counterparts (128 and 73 mW cm-2). This research provides a pivotal foundation for the evolution of bifunctional catalysts in the energy sector.

Conductivity-enhanced porous N/P co-doped metal-free carbon significantly enhances oxygen reduction kinetics for aqueous/flexible zinc-air batteries.

Heteroatom-doped metal-free carbon catalysts for oxygen reduction reactions have gained significant attention because of their unusual activity and economic cost. Here, a novel N/P co-doped porous carbon catalyst (NPPC) with a high surface area for oxygen reduction reaction (ORR) is constructed by a facile high-temperature calcination method employing ZIF-8 as the precursor and red phosphorus as the phosphorus source. In particular, ZIF-8 is firstly calcined to obtain N-doped carbon (NC) followed by further calcination with red phosphorus to obtain NPPC. Ultraviolet photoelectron spectroscopy (UPS) analysis shows that the ultra-low amount of P doping could significantly decrease the work function from 4.32 to 3.86 eV. The resultant catalyst exhibits a promising electrocatalytic activity with a half-wave potential (E1/2) of 0.87 V and a limiting current density (JL) of 5.15 mA cm-2. Besides, it also shows improved catalytic efficiency and excellent durability with a negligible decay of JL after 2000 CV cycles. Moreover, aqueous and solid-state flexible zinc-air batteries (ZAB) using the catalyst show a promising application potential. This work provides new insight into developing P/N-doped metal-free carbon ORR catalysts.

Fine-tune d-band center of cobalt vanadium oxide nanosheets by N-doping as a robust overall water splitting electrocatalyst.

Developing high-activity, long-durability, and noble metal-free oxygen evolution (OER) and hydrogen evolution (HER) cocatalysts are the bottlenecks for efficient overall water splitting (OWS). Here, novel cobalt vanadium oxides doped by nitrogen were synthesized by nitriding Co2V2O7@NF precursor at 300-450 °C for OER and HER reactions. N-Co2V2O7@NF (350 °C) and N-Co2VO4/VO2@NF (400 °C) show remarkable OER and HER performance with overpotentials of 310 mV and 224 mV at high current density (100 mA cm-2). Besides, they also revealed long-term solid stability even after 170 h and 700 h of continuous performance. Furthermore, the N-Co2V2O7@NF(+)||N-Co2VO4/VO2@NF(-) OWS device possesses a cell voltage of 1.93 V at 500 mA cm-2 better than RuO2@NF(+)||Pt/C@NF(-) (2.02 V) and can operate for 60 h with almost no degradation. This extraordinary performance can be attributed to the nanosheet structure, which can maximize the exposure of active sites and accelerate the mass transfer. Moreover, density functional theory (DFT) calculations suggest that N-doping can fine-tune the d-band center and band gap to facilitate intermediate adsorption and electron motion. The method presented here can be applied in other novel N-doped electrocatalysts for the energy field.

Improving the Electrocatalytic Activity of a Nickel-Organic Framework toward the Oxygen Evolution Reaction through Vanadium Doping.

Metal-organic frameworks (MOFs) have been considered as potential oxygen evolution reaction (OER) electrocatalysts owning to their ultra-thin structure, adjustable composition, high surface area, and high porosity. Here, we designed and fabricated a vanadium-doped nickel organic framework (V1-x -Nix MOF) system by using a facile two-step solvothermal method on nickel foam (NF). The doping of vanadium remarkably elevates the OER activity of V1-x -Nix MOF, thus demonstrating better performance than the corresponding single metallic Ni-MOF, NiV-MOF and RuO2 catalysts at high current density (>400 mA cm-2 ). V0.09 -Ni0.91 MOF/NF provides a low overpotential of 235 mV and a small Tafel slope of 30.3 mV dec-1 at a current density of 10 mA cm-2 . More importantly, a water-splitting device assembled with Pt/C/NF and V0.09 -Ni0.91 MOF/NF as cathode and anode yielded a cell voltage of 1.96 V@1000 mA cm-2 , thereby outperforming the-state-of-the-art RuO2 (+) ||Pt/C(-) . Our work sheds new insight on preparing stable, efficient OER electrocatalysts and a promising method for designing various MOF-based materials.

Co4S3 grafted 1 T-phase dominated WS2 ultrathin nanosheet arrays for highly efficient overall water splitting in alkaline media.

Developing the earth-abundant transition metal-based bifunctional electrocatalysts for water splitting and renewable energy devices has attracted much attention. Herein, we report a 1 T-WS2 in ultrathin nanosheet arrays grafted with Co4S3 on conductive carbon cloth (CC) (1 T-Co4S3-WS2/CC) through a feasible in-situ growth and vulcanization. The optimized 1 T-Co4S3-WS2/CC catalyst exhibits an impressive electrocatalytic activity and remarkable stability with the oxygen/hydrogen evolution reaction (OER/HER: 278/75 mV for 10 mA cm-2). It also showed the small Tafel slope values of 61.7 and 58.4 mV dec-1, respectively. Additionally, the 1 T-Co4S3-WS2/CC(-/+) achieved 1.59 V@10 mA cm-2 in alkaline media superior to the most previously reported non-precious metal electrocatalysts. The outstanding performance could be attributed to the synergy between heterostructures of Co4S3 and 1 T-WS2 modifying the electronic structure to accelerate water splitting kinetics. Thus, this work presents a rational design of scalable, high-efficiency, stable water splitting electrocatalysts based on WS2.

Single-incision laparoscopic versus conventional laparoscopic right colectomy: A systematic review and meta-analysis.

BACKGROUND: Single-incision laparoscopic surgery has gained widespread attention because of its potential benefits such as less skin incision and faster recovery. Up to now, only one meta-analysis (performed in 2013; including 9 studies, a total of 585 cases) compared single-incision laparoscopic right colectomy (SILRC) with conventional laparoscopic right colectomy (CLRC). An updated meta-analysis was undertaken to explore more convinced comparative findings between SILRC and CLRC. MATERIALS AND METHODS: The search for studies that compared SILRC with CLRC was done on PubMed, Embase, Web of Science, and the Cochrane Library. A total of 17 studies (including 1778 cases) were identified, the data of appointed outcomes were extracted and analyzed. RESULTS: Patient demographics (age, gender, body mass index and previous abdominal operation) did not differ significantly. No significant differences were found between SILRC and CLRC in operative time, conversion, reoperation, perioperative complications, postoperative mortality, and 30-days readmission. Pathological outcomes, including lymph nodes harvested, proximal resection margin, and distal resection margin, were similar. SILRC showed less estimated blood loss (weighted mean difference [WMD]: -15.67 ml; 95% confidence interval [CI], -24.36 to -6.98; p = 0.0004), less skin incisions (WMD: -1.56 cm; 95%CI, -2.63 to -0.49; p = 0.004) and shorter hospital stay (WMD: -0.73d; 95%CI, -1.04 to -0.41; p < 0.00001), without publication bias. CONCLUSION: SILRC may provide a safe and feasible alternative to CLRC with similar short-term outcomes and aesthetic advantage of less skin incision. Well-designed randomized controlled trials, involving large cases and carrying long-term outcomes, are needed.