Catalysts For Electrochemical Water Splitting Research Articles

One-pot synthesis of metal-carbon nanotubes network hybrids as highly efficient catalysts for oxygen evolution reaction of water splitting.

Oxygen evaluation reaction (OER) is the most important reaction in hydrogen production from water splitting. Here we developed metal-carbon nanotubes (M-CNTs) hybrids with high metal oxide catalyst loading synthesized by arc-discharge and chemical vapor deposition (CVD) methods as electrocatalysts for OER in alkaline solutions. The M-CNTs hybrids produced by arc-discharge (M-CNTs-Arc) and CVD (M-CNTs-CVD) exhibit a core-shell-like structure, in which metal nanoparticles (NPs) encapsulated by graphite shells are connected by carbon nanotubes (CNTs), forming M-CNTs network hybrids. M-CNTs-Arc has NiCo0.16Fe0.34 metal core and shows very high activity and superior stability for OER, achieving 100 A g(-1) at an overpotential (η) of 0.29 V and 500 A g(-1) at η = 0.37 V in 1 M KOH solution. This is probably the highest activity reported for OER in alkaline solutions. The reaction follows the first-order kinetics with respect to OH(-) concentration and Tafel slope of 34 mV dec(-1). The results demonstrate a highly efficient, scalable, and low-cost one-step synthesis method for developing highly active and stable catalysts for electrochemical water splitting in alkaline solutions.

Sputtered iridium oxide films as electrocatalysts for water splitting via PEM electrolysis

Thin films of iridium oxide deposited by reactive magnetron sputtering have been investigated as catalysts for electrochemical water splitting in a polymer electrolyte membrane (PEM) cell. The sputtered films possess excellent mechanical stability and corrosion resistance at the high anodic potentials where oxygen evolution takes place. Their catalytic activity has been assessed using the conventional electrochemical methods of cyclovoltammetry and steady state polarisation techniques. A morphology factor assessing the catalyst active surface for a series of sputtered samples with varying thickness/loading has been determined and correlated to the catalytic efficiency. It has been proven that iridium oxide is a very efficient catalyst for oxygen evolution reaction (OER). The best performance with anodic current density of 0.3 A cm −2 at potential of 1.55 V (versus RHE) has shown the 500 nm thick film containing 0.2 mg cm −2 catalyst. The results obtained have also demonstrated the advantages of the reactive magnetron sputtering as simple and reliable method for deposition of efficient and cost effective catalysts for PEM electrolysis application.

Exploiting synergy between FCC and feed pretreating units to improve refinery margins and produce low-sulfur fuels

The development of high performance bi-functional electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with low cost materials has remained a great challenge in electrochemical water splitting. Herein, we design and develop novel Co-doped Fe0.95S1.05 nanoplates, which were synthesized using Fe(CO)5 as precursor for the first time via a one pot reaction. Fe0.9Co0.05S1.05 lead to enhanced OER activity with a low overpotential of ∼ 0.27 V at 20 mA/cm2, small Tafel slope of ∼ 46 mV/decade, as well as improved HER activity with a Tafel slope of 114 mV/decade and a current density of 20 mA/cm2 at an overpotential of ∼ 0.385 V. This study produced the most active pyrrhotite FeS based catalyst for electrochemical water splitting, which suggests a scalable, low cost, simple, and highly efficient catalyst for water splitting.