Researchers belonging to the University of Houston have had a significant breakthrough with a new oxygen evolution reaction catalyst which, when combined with hydrogen evolution reaction catalysts, was able to achieve current densities that can support industrial demands, while consuming relatively low voltage to commence seawater electrolysis. The team says that the device, consisting of inexpensive non-noble metal nitrides, can avoid several of the obstacles that have restricted earlier attempts to produce hydrogen or safe drinkable water from seawater cost-effectively. The research has been outlined in the journal Nature Communications.
Zhifeng Ren, Director, Texas Center for Superconductivity, University of Houston, and a co-author of the paper, says that the lack of a catalyst that can effectively split seawater to generate hydrogen without setting free ions of calcium, chlorine, sodium, and other components, found in seawater that might settle on the catalyst once free, leaving it inactive, has been a significant hurdle in the development of such as mechanism. The team tested the catalysts with seawater from Galveston Bay off the Texas coast. Professor Ren, M.D. Anderson Chair Professor, Physics, University of Houston, says it would also work with wastewater, offering another source of hydrogen from water, which otherwise cannot be used without undergoing costly treatment. Typically people use freshwater to produce hydrogen, but clean freshwater has limited availability. To address this issue, the team designed an synthesized a three-dimensional core-shell oxygen evolution reaction catalyst with transition metal-nitride, with nanoparticles made with nickel-iron-nitride compound and nickel-molybdenum-nitride nanorods on porous nickel foam.
The first author, Luo Yu, a postdoctoral candidate at the university, says that the new oxygen evolution reaction catalyst was paired with a formerly reported hydrogen evolution reaction catalyst of nickel-molybdenum-nitride nanorods. The catalysts were fused into a two-electrode alkaline electrolyzer, which can run on waste heat through a thermoelectric device or an AA battery. Cell voltages ranging between 1.564 V to 1.581 V was able to generate a current density of 100 milliamperes per square centimeter or mA cm-2.