Pt- and Pd-modified transition metal nitride catalysts for the hydrogen evolution reaction

Hydrogen production via electrochemical splitting of water using renewable electricity represents a promising strategy. Currently, platinum group metals (PGMs) are the best performing hydrogen evolution reaction (HER) catalysts. Thus, the design of non-PGM catalysts or low-loading PGM catalysts is essential for the commercial development of hydrogen generation technologies via electrochemical splitting of water. Here, we employed density functional theory (DFT) calculations to explore Pt and Pd modified transition metal nitrides (TMNs) as low-cost HER catalysts. Our calculations show that Pt/Pd binds strongly with TMs on TMN(111) surfaces, leading to the formation of stable Pt and Pd-monolayer (ML)-TMN(111) structures. Furthermore, our calculated hydrogen binding energy (HBE) demonstrates that Pt/MnN, Pt/TiN, Pt/FeN, Pt/VN, Pt/HfN, Pd/FeN, Pd/TaN, Pd/NbN, Pd/TiN, Pd/HfN, Pd/MnN, Pd/ScN, Pd/VN, and Pd/ZrN are promising candidates for the HER with a low value of limiting potential (U_L) similar to that calculated on Pt(111).

Density functional theory studies of transition metal carbides and nitrides as electrocatalysts

Transition metal carbides and nitrides are interesting non-precious materials that have been shown to replace or reduce the loading of precious metals for catalyzing several important electrochemical reactions. The purpose of this review is to summarize density functional theory (DFT) studies, describe reaction pathways, identify activity and selectivity descriptors, and present a future outlook in designing carbide and nitride catalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), nitrogen reduction reaction (N₂RR), CO₂ reduction reaction (CO₂RR) and alcohol oxidation reactions. This topic is of high interest to scientific communities working in the field of electrocatalysis and this review should provide theoretical guidance for the rational design of improved carbide and nitride electrocatalysts.

Exploring fuel cell cathode materials using ab initio high throughput calculations and validation using carbon supported Pt alloy catalysts

We employ a combined density functional theory (DFT) and experimental approach to screen different elements (M) and Pt₃M alloys (M = Sc, Y, V, Nb, Ta, Ti, Zr, Hf, Cr, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Cu, Ag, Au and Al) for oxygen reduction reaction (ORR) activity and stability. The results of the calculations are validated using a series of carbon supported alloy nanoparticles measured within membrane electrode assembly (MEA) environments. We assess the reliability of descriptors such as surface d-band centre and O adsorption energy as computed from DFT calculations. We also assess the stability of the alloy surfaces under different adsorbate environments as encountered under ORR conditions. Our calculations predict that under an oxygen atmosphere segregation of M to the surface is likely to occur. The calculated segregation energies correlate reasonably well with the amount of base metal leached in the carbon-supported catalysts and good correlation of computed O adsorption energies with ORR activity is also shown.

Enhanced Stability of PtML/MML/WC(0001) Multilayer Alloys under Electrochemical Conditions: A First Principle Study

A platinum (Pt) monolayer catalyst could greatly reduce the use of Pt. However, the core or subsurface transition metal could easily segregate to the surface and eventually selectively dissolve in the working conditions. In this work, a type of Pt_ML/M_ML/tungsten carbide (WC) multilayer structure catalyst has been designed using the density functional theory method. The results show that the stability of W-terminated core catalysts is lower than that of the corresponding C-terminated one. More importantly, the C-terminated Pt_ML/Co_ML/WC alloy could also maintain a stable Pt monolayer structure in various electrolyte solutions (e.g., perchloric acid, phosphoric acid, and alkaline solutions) and via different oxygen reduction reaction (ORR) pathways, in addition to the previously well-known precious alloy elements, such as Ru, Ir, and so forth. The segregation of the M metal will be suppressed by introducing a high electronegativity nonmetal element in the core such as C through enhanced interaction between the C and M interlayers. The improved ORR activity and the stability of C-terminated Pt_ML/Co(Ru)_ML/WC(0001) multilayer structures highlight the importance of surface chemistry of the substrate in rational design Pt monolayer catalysts.

Ethanol, O, and CO adsorption on Pt nanoparticles: effects of nanoparticle size and graphene support

DFT calculations reveal aspects of size and support effects for Pt nanoparticles on graphene interacting with O, CO and ethanol.

Tuning core–shell interactions in tungsten carbide–Pt nanoparticles for the hydrogen evolution reaction

Titanium doping enhances the stability and activity of tungsten carbide core–platinum shell nanoparticles for hydrogen evolution

Elucidating the degradation mechanism of the cathode catalyst of PEFCs by a combination of electrochemical methods and X-ray fluorescence spectroscopy

In this study, we report a methodology which enables the determination of the degradation mechanisms responsible for catalyst deterioration under different accelerated stress protocols (ASPs) by combining measurements of the electrochemical surface area (ECSA) and Pt content (by X-ray fluorescence).

Effect of graphene support on large Pt nanoparticles

Large scale DFT calculations of Pt nanoparticles supported on graphene explore the non-trivial interplay of size and support effects.