Carbon-supported PtRu alloy films are emerging as promising catalysts, combining excellent catalytic properties with stability and conductivity to create next-generation electrodes for hydrogen production.
Green hydrogen—a clean fuel produced by splitting water with renewable electricity—holds the key to decarbonizing our economy. At the heart of this revolution are advanced materials that make hydrogen production efficient and affordable. Among them, carbon-supported PtRu alloy films are emerging as particularly promising candidates, combining the excellent catalytic properties of precious metals with the stability and conductivity of carbon supports to create next-generation electrodes for hydrogen production.
PtRu alloys demonstrate exceptional activity in both acidic and alkaline conditions 1 .
Ruthenium is more abundant and cheaper than platinum, reducing catalyst costs.
The hydrogen evolution reaction (HER) is the crucial half-reaction where hydrogen gas is formed during water electrolysis. While platinum has long been the champion catalyst for this process, its scarcity and high cost have driven scientists to search for alternatives that use less platinum while maintaining or even enhancing performance.
The introduction of ruthenium (Ru) to create platinum-ruthenium (PtRu) alloys represents a strategic breakthrough. Ruthenium is more abundant and cheaper than platinum, and when combined, these two metals create a synergistic effect where the alloy performs better than either metal alone.
Recent studies have revealed that these benefits extend across different environments, with PtRu alloys demonstrating exceptional activity in both acidic and alkaline conditions 1 —a valuable characteristic for practical electrolyzer systems that may operate under varying conditions.
PtRu alloys create a synergistic effect where the combination performs better than either metal alone.
Researchers employed a salt-template-assisted pyrolysis strategy to create extraordinarily small PtRu alloy nanoparticles embedded in ultrathin carbon nanosheets 1 .
The resulting catalyst, labeled Pt₂Ru/C, features particles smaller than 2 nanometers—so tiny that about 500 could fit across a human hair.
Scientists are now moving beyond simple binary alloys to explore more complex compositions. Research has demonstrated that incorporating additional elements such as nickel into PtRu systems can create even more effective catalysts 2 .
One study reported a remarkable achievement: a CP-PtNiRu electrocatalyst requiring only 30.5 mV overpotential to reach 10 mA/cm² in acidic conditions.
| Catalyst Type | Overpotential at 10 mA/cm² | Reaction Medium | Key Advantage |
|---|---|---|---|
| Pt₂Ru/C nanosheets 1 | Low (specific value not provided) | Acid & Alkaline | Dual functionality |
| CP-PtNiRu 2 | 30.5 mV | Acidic | Excellent activity |
| Ir₃₆Pd₄Pt₄₈Ru₁₂ HEA 3 | Not specified | Alkaline | Multi-element synergy |
Even more complex high-entropy alloys containing four or more elements are being explored. One systematic investigation examined Cu-Pd-Pt-Ru, Ir-Pd-Pt-Ru, and Ni-Pd-Pt-Ru systems, discovering that specific compositions such as Ir₃₆Pd₄Pt₄₈Ru₁₂ surpassed the performance of any single metallic element by 26% for hydrogen evolution 3 .
To understand how scientists achieve these remarkable materials, let's examine the salt-template-assisted pyrolysis approach used to create sub-2 nm PtRu alloys—a method that exemplifies the ingenuity in modern catalyst design 1 .
Researchers begin with a salt template that provides a structured foundation for material growth. This template will later be removed, leaving behind precisely controlled porous structures.
Solutions containing platinum and ruthenium precursors are introduced to the template, ensuring uniform distribution of both metals at the atomic level.
The material undergoes carefully programmed heating in an inert atmosphere. This pyrolysis step transforms the metal precursors into crystalline PtRu alloy nanoparticles while simultaneously converting carbon sources into conductive graphene-like nanosheets.
The salt template is washed away, revealing a free-standing network of ultrathin carbon nanosheets with embedded PtRu nanoparticles.
The final material is activated and assembled into electrodes for systematic performance evaluation in both acidic and alkaline electrolytes.
The experimental results demonstrated why this approach generates such excitement. The Pt₂Ru/C catalyst exhibited exceptional activity for hydrogen evolution across the pH spectrum. In alkaline conditions, the catalyst maintained stable performance, addressing one of the traditional challenges in water splitting where catalysts often perform well in either acid or base but rarely both 1 .
The carbon nanosheets serve as more than just support; they protect the alloy nanoparticles from dissolving or aggregating during prolonged operation, addressing the critical challenge of catalyst durability.
This structural integrity translates to consistent performance over time, an essential requirement for commercial applications where electrolyzers must operate for thousands of hours.
Recent investigations into the fundamental mechanisms have revealed that the oxidation states of both platinum and ruthenium play crucial roles in the enhanced catalytic performance 5 . The interaction between the metals creates electronic structure modifications that optimize the binding energy of hydrogen intermediates—a key factor in catalytic efficiency.
This synergistic effect can be understood through what researchers describe as a "capturing and releasing mechanism" where one element preferentially attracts reaction intermediates while the other facilitates their conversion to final products 5 .
Interestingly, the utility of PtRu systems extends beyond hydrogen production. Recent studies have explored their application in ammonia oxidation 4 , revealing that the presence of metallic ruthenium in PtRu/C catalysts significantly lowers the onset potential for nitrogen production by 100 mV compared to pure platinum catalysts 4 . This versatility across different electrochemical reactions underscores the fundamental advantages of the PtRu combination.
| Application | Reaction | Key Finding | Significance |
|---|---|---|---|
| Ammonia Oxidation 4 | AOR | 100 mV lower N₂ onset potential | Advancements for ammonia fuel cells |
| Methanol Oxidation | MOR | Superior to many reported catalysts | Application in direct methanol fuel cells |
Advancements in PtRu catalyst development rely on sophisticated experimental approaches and specialized materials.
Create controlled porous structures for generating ultrathin carbon nanosheets with embedded nanoparticles 1 .
Rapidly form alloy nanoparticles for producing multicomponent alloys on carbon paper 2 .
Rapid screening of compositional libraries for efficient exploration of high-entropy alloy systems 3 .
Detect gaseous reaction products for identifying nitrogen products in ammonia oxidation 4 .
The development of carbon-supported PtRu alloy films continues to evolve, with several promising directions emerging. The combinatorial exploration of multi-element systems represents a powerful strategy for discovering novel catalysts with enhanced performance 3 . Additionally, researchers are working to scale up production methods while further reducing platinum content without compromising activity.
The ultimate goal remains the cost-effective production of green hydrogen at a scale that can meaningfully impact our energy systems. With continued refinement of PtRu alloy catalysts and their integration into efficient electrolyzer designs, this goal appears increasingly attainable.
As research progresses, these sophisticated materials are poised to play a pivotal role in the transition to a sustainable hydrogen economy—proving that sometimes the smallest things, like sub-2 nanometer particles, can make the biggest impact on our planet's future.
PtRu alloy catalysts represent a critical advancement in making green hydrogen production more efficient and economically viable.