Liquefied Sunshine: Transforming Renewables into Fertilizers and Energy Carriers with Electromaterials

Abstract

It has become apparent that renewable energy sources are plentiful in many, often remote, parts of the world, such that storing and transporting that energy has become the key challenge. For long‐distance transportation by pipeline and bulk tanker, a liquid form of energy carrier is ideal, focusing attention on liquid hydrogen and ammonia. Development of high‐activity and selectivity electrocatalyst materials to produce these energy carriers by reductive electrochemistry has therefore become an important area of research. Here, recent developments and challenges in the field of electrocatalytic materials for these processes are discussed, including the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the nitrogen reduction reaction (NRR). Some of the mis‐steps currently plaguing the nitrogen reduction to ammonia field are highlighted. The rapidly growing roles that in situ/operando and quantum chemical studies can play in new electromaterials discovery are also surveyed.

Rejuvenating the Geometric Electrocatalytic OER Performance of Crystalline Co3O4 by Microstructure Engineering with Sulfate

“…Development of transition metal (TM)-based compounds as electrocatalysts to promote the kinetics of water splitting reaction is of pivotal importance for stimulating the wide-scale production and adoption of hydrogen as a sustainable fuel due to their relatively low cost and higher abundance compared to the noble metal based electrocatalysts (Pt, RuO 2 , etc.). [1][2] While the hydrogen evolution half-reaction (HER) in the cathode requires two electrons, the oxygen evolution half-reaction (OER) at anode involves the transfer of four electrons. The involvement of higher number of electrons makes OER the bottleneck for overall water splitting performance of a cell.…”

Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

“…Water electrolysers based on a proton-exchange membrane (PEM) electrolyte are currently seen as the preferred technology for the production of green hydrogen from renewables. [1][2] Double digit megawatt PEM plants are already available and even larger installations are planned. 3 Recent breakthroughs in the design of bipolar plates and cathode catalysts for the PEM electrolysers now throw a spotlight on the membrane and anode electrocatalysts as the components requiring further significant cost-efficiency improvements.…”

Insights into Nitrogenase Bioelectrocatalysis for Green Ammonia Production

“…To export hydrogen from regions with high renewable energy intensity to those lean in renewable energy requires hydrogen to be in a form that is transportable . Liquification of hydrogen is very energy intensive, as it requires gaseous hydrogen to be cooled to below −253 °C.…”

“…Of these options, ammonia is possibly the most attractive hydrogen carrier, as it does not produce CO 2 when it is decomposed and it can be readily liquified by compression to 10 bar or cooling to −33 °C. In addition, ammonia for fertilizer is already routinely transported around the world with mature infrastructure for handling, shipping, and safety already in existence . Importantly, in recent years significant advances have been made in both NH 3 decomposition catalysts and membranes for hydrogen separation .…”