다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Recent Progress of Vacancy Engineering for Electrochemical Energy Conversion Related Applications

Corrosion Engineering on Iron Foam toward Efficiently Electrocatalytic Overall Water Splitting Powered by Sustainable Energy

In this work, several commonly used conductive substrates as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions were studied, including nickel foam (Ni foam), copper foam (Cu foam), nickel mesh (Ni mesh) and stainless steel mesh (SS mesh). Ni foam and SS mesh are demonstrated as high-performance and stable electrocatalysts for HER and OER, respectively. For HER, Ni foam exhibited an overpotential of 0.217 V at a current density of 10 mA cm−2 with a Tafel slope of 130 mV dec−1, which were larger than that of the commercial Pt/C catalyst, but smaller than that of the other conductive substrates. Meanwhile, the SS mesh showed the best electrocatalytic performance for OER with an overpotential of 0.277 V at a current density of 10 mA cm−2 and a Tafel slope of 51 mV dec−1. Its electrocatalytic performance not only exceeded those of the other conductive substrates but also the commercial RuO2 catalyst. Moreover, both Ni foam and SS mesh exhibited high stability during HER and OER, respectively. Furthermore, in the two-electrode system with Ni foam used as the cathode and SS mesh used as the anode, they enable a current density of 10 mA cm−2 at a small cell voltage of 1.74 V. This value is comparable to or exceeding the values of previously reported electrocatalysts for overall water splitting. In addition, NiO on the surface of Ni foam may be the real active species for HER, NiO and FeOx on the surface of SS mesh may be the active species for OER. The abundant and commercial availability, long-term stability and low-cost property of nickel foam and stainless steel mesh enable their large-scale practical application in water splitting.

https://pubs.rsc.org/en/content/articlepdf/2019/RA/C9RA07258F

Nickel foam and stainless steel mesh as electrocatalysts for hydrogen evolution reaction, oxygen evolution reaction and overall water splitting in alkaline media

Rare earth (RE) elements have drawn increased attention recently as an effective promoter in electrocatalysis because of their partially filled 4f orbitals. Herein, a new type of RE hybrid electrocatalyst, consisting of a gadolinium-doped hierarchal NiFe-layered double hydroxide in situ grown on carbon cloth (Gd-NiFe-LDH@CC), is designed and developed via a facile one-step hydrothermal approach. The Gd doping regulates the electronic structure of NiFe-LDH and increases the number of oxygen vacancies, thus tuning the adsorption energies of oxygen intermediate species (e.g. HOO*). With the presence of Gd species, Gd-NiFe-LDH@CC exhibits superior electrocatalytic activity for the OER in an alkaline medium, which requires an overpotential of only 210 mV to afford 10 mA cm−2 current density, better than that of NiFe-LDH@CC (250 mV) and commercial RuO2 (298 mV). The robust electrocatalytic stability and satisfactory selectivity (nearly 100% Faraday efficiency) of Gd-NiFe-LDH@CC for the OER are also demonstrated. We ascribe such outstanding OER performance of Gd-NiFe-LDH@CC to the optimized electronic structure, rich oxygen vacancies and hierarchal porous morphology. Theoretical calculation further demonstrates that the electronic disturbance caused by Gd doping enhances the activity of Ni sites, resulting in stronger binding strength of HOO* at the Ni sites during the OER.

Gd-induced electronic structure engineering of a NiFe-layered double hydroxide for efficient oxygen evolution

Design of cost-effective bifunctional electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is vital for developing hydrogen energy for the future. Herein, a cost-effective phosphorus-doped Co–Fe–B material with chain-like structure (denoted as Co1–Fe1–B–P) is reported as an efficient and novel bifunctional electrocatalyst for the OER and HER, and was produced via a facile water-bath synthesis and subsequent phosphorization. For the OER, the as-prepared Co1–Fe1–B–P nanochains require an extremely low overpotential of about 225 mV at 10 mA cm−2 and possess a small Tafel slope of 40 mV dec−1 in alkaline media. Impressively, the HER properties of Co1–Fe1–B–P nanochains are superior to those of P-free Co–Fe–B in terms of overpotential at 10 mA cm−2 (173 mV vs. 239 mV) and kinetic Tafel slope (96 mV dec−1vs. 105 mV dec−1). The synergetic effect between Co–Fe–B and doped-P is mainly responsible for the satisfactory bifunctional performance, while the one-dimensional (1D) chain-like structure endows Co1–Fe1–B–P with abundant catalytically active sites that enhance the atom utilization efficiency. Moreover, the developed Co1–Fe1–B–P nanochains can be simultaneously utilized as both the cathode and anode for overall water-splitting, which requires a cell voltage of only 1.68 V to deliver 10 mA cm−2. This work provides a feasible and promising protocol to realize metal borides as efficient electrocatalysts in energy-related applications.

Dazong Nie

Papers

Facile synthesis of Co-Fe-B-P nanochains as an efficient bifunctional electrocatalyst for overall water-splitting.