Abstract
Transition-metal phosphides (TMPs) are versatile materials with tunable electronic and structural properties that have led to exceptional catalytic performances for important energy applications. Identifying predictive relationships between the catalytic performance and key features such as the composition, morphology, and crystalline structure hinges on the ability to independently tune these variables within a TMP system. Here, we have developed a versatile, low-temperature solution synthesis route to alloyed nickel phosphide (Ni1.6M0.4P, where M = Co, Cu, Mo, Pd, Rh, or Ru) nanoparticles (NPs) that retains the structure of the parent Ni2P NPs, allowing investigation of compositional effects on activity without convoluting factors from differences in morphology and crystalline phase. As a measure of the controlled changes introduced within the isostructural series by the second metal, the binary and alloyed ternary TMP NPs supported on carbon at a nominal 5% weight loading were studied as electrocatalysts for the hydrogen evolution reaction (HER). The resultant activity of the electrocatalyst series spanned a 125 mV range in overpotential, and composition-dependent trends were investigated using density functional theory calculations on flat (0001) and corrugated (101¯ 0) Ni1.67M0.33P surfaces. Applying the adsorption free energy of atomic H (GH) as a descriptor for HER activity revealed a facet-dependent volcano-shaped correlation between the overpotential and GH, with the activity trend well represented by the corrugated (101¯ 0) surfaces on which metal-metal bridge sites are available for H adsorption but not the flat (0001) surfaces. The versatility of the rational synthetic methodology allows for the preparation of a wide range of compositionally diverse TMP NPs, enabling the investigation of critical composition-performance relationships for energy applications.
| Original language | English |
|---|---|
| Pages (from-to) | 6255-6267 |
| Number of pages | 13 |
| Journal | Chemistry of Materials |
| Volume | 34 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 26 2022 |
Funding
This work was authored in part by the National Renewable Energy Laboratory (NREL), operated by Alliance for Sustainable Energy, LLC, and in part by the Oak Ridge National Laboratory, operated by UT-Battelle, LLC, for the U.S. Department of Energy (DOE) under contract nos. DE-AC36-08GO28308 and DE-AC05-00OR22725, respectively. This work was supported by the Laboratory Directed Research and Development (LDRD) program at NREL. Support for this work was also provided by the U.S. DOE Office of Energy Efficiency and Renewable Energy Bioenergy Technologies Office. This research was conducted in collaboration with the Chemical Catalysis for Bioenergy (ChemCatBio) Consortium, a member of the Energy Materials Network (EMN). Part of the microscopy was supported by Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE, Office of Science User Facility. STEM-EDS microscopy research was performed using instrumentation (FEI Talos F200X S/TEM) provided by the U.S. DOE, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. Computational modeling was performed using computational resources sponsored by the U.S. DOE Office of Energy Efficiency and Renewable Energy and located at NREL. Authors thank Vassili Vorotnikov for collaboration on computational modeling, Anne K. Starace for performing thermogravimetric analysis, and Shawn K. Reeves for assistance with TEM sample preparation. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.
