Rhodium/Carbon (Rh/C, Premetek) as Electrocatalysts for Electrolyzer and Fuel Cell, 0.5 g/bottle, CEFCERhC

Rhodium on Carbon (Rh/C) is a specialized noble metal electrocatalyst that bridges the gap between the high activity of platinum and the unique requirements of alkaline and chemical synthesis systems. While it shares many properties with Pt/C, it is often selected for its superior water-splitting kinetics in non-acidic media and its resilience in complex organic reactions.

While Platinum is the benchmark for the Hydrogen Evolution Reaction (HER) in acid, Rh/C is often superior in alkaline water electrolysis. (1) Water Dissociation (Volmer Step): In alkaline media, the reaction must first "break" a water molecule (H2O) to get a proton. Rhodium has a much lower energy barrier for this water dissociation step than Platinum, making it significantly more efficient in basic solutions. (2) Optimal Binding Energy: Rhodium sits at the top of the "volcano plot" for hydrogen adsorption, meaning it binds hydrogen atoms perfectly-strong enough to react, but weak enough to release as H2 gas. (3) Bimetallic Synergies: It is frequently alloyed with copper (Rh-Cu/C) or nickel to create nanotubes or porous structures that outperform pure Pt/C by optimizing the surface charge environment.

In fuel cells, Rh/C is rarely used as a general-purpose cathode but is a powerful tool for specialized anodes. (1) Direct Ammonia Fuel Cells (DAFC): Rh/C is one of the most active catalysts for the Ammonia Oxidation Reaction (AOR). It is uniquely selective toward producing nitrogen gas (N2) rather than harmful nitrogen oxides, making it the primary candidate for "green ammonia" power systems. (2) CO-Tolerant Hydrogen Oxidation: Rh/C is highly resistant to Carbon Monoxide (CO) poisoning. Like Ruthenium, it facilitates a bifunctional mechanism where it provides oxygen-containing species at lower voltages to "clean" CO off the catalyst surface, allowing the cell to run on reformed hydrogen. (3) Alcohol Oxidation: It is used as a co-catalyst in Direct Ethanol or Methanol Fuel Cells to help break C-C bonds and manage reaction intermediates.

In CO2 Reduction (CO2RR) application field, Rhodium plays a key role in converting CO2 into valuable chemicals like methane (CH4) or acetic acid. It is particularly known for high selectivity—when exposed to light (photocatalysis), Rh nanoparticles can show a seven-fold increase in methane production compared to traditional thermal methods.

Notes: Please try to store the Rh/C powder in a dry place.

References: 

1. H. Wang, et al. Rh and Rh Alloy Nanoparticles as Highly Active H2 Oxidation Catalysts for Alkaline Fuel Cells, ACS Catal. 2019, 9, 6, 5057–5062.
2. Z. H. Yuan, et al. Architecture Engineering and Phase Engineering of Rhodium Metallene Co-Boost Nitrite-to-Ammonia Electroconversion, Angew Chem Int. Ed, 2025, 64, e202509944.