Combinatorial Synthesis and Screening of a Ternary NiFeCoO_x Library for the Oxygen Evolution Reaction

Abstract

The development of an efficient catalyst for the oxygen evolution reaction (OER) is critical to fulfilling the mission of hydrogen generation by water splitting. Various multicomponent systems have been investigated so far for the OER, although a systematic investigation is lacking and there are discrepancies as to which formulations make the best catalyst. Here, we perform a systematic investigation of a ternary Ni-Fe-Co oxide gradient library for the OER, using a combinatorial approach. This approach allows a much faster investigation of a vast compositional space compared to the traditional step by step approach. Also, it enables a more reliable comparison of the various catalysts as they all experience the same process and measurement conditions. We used the spray pyrolysis technique in combinatorial electrocatalyst screening for the first time for the generation of a gradient library of Ni-Fe-Co oxides. Combinatorial electrochemical screening using a scanning droplet cell (SDC) set up allowed the study of 94 different points in the compositional space of the trimetallic Ni-Fe-Co oxide library, which was used to deduce a composition–activity relationship. At 10 mA cm–2, the investigated points spanned an overpotential window of 294–320 mV, with the best performing ternary oxides being confined to a compositional space of 4–15% Fe, 4–15% Co, and 80–90% Ni. This study provides a foundation for broad exploration of other mixed-metal oxide combinations.

Exploration of a NiFeV multi-metal compositional space for the oxygen evolution reaction

“…10,[60][61][62] In our previous work, we have shown that the addition of modest amounts of cobalt to the NiFe system can have a significant impact on the OER activity. 29 Various such transition elements (Cr, Ce, V, Mn) owing to their tuneable d-band structure, have been incorporated into the standard NiFe system to improve its catalytic properties. [63][64][65][66][67] In the study of multimetal alloys, obtaining the same volume of data as we obtained and effectively spanning the same compositional space as achieved in our work would require a substantially higher number of experiments, time, and cost.…”

“…In our previous work, we demonstrated the incorporation of Fe and Co into a Ni matrix as an effective strategy to improve the catalytic performance. 29 Although cobalt improves the OER performance, cobalt is a critical raw material and its mining raises environmental, social, and governance issues. Herein, we chose vanadium as a suitable candidate to drive down the overpotential of the NiFe based catalysts relying on vanadium's multivalency, relative abundance, 30 and stability.…”

Advances in Functional Ceramics for Water Splitting: A Comprehensive Review

“…Nanoscale porosity in mixed metal phosphonates, such as Ni-W mixed metal phosphonate, has been found to be responsible for efficient photoelectrochemical OER in alkaline conditions, showcasing the versatility of these materials in harnessing solar energy for water splitting [97]. Furthermore, the combinatorial synthesis and screening of ternary NiFeCoO x libraries have provided insights into the optimization of mixed metal oxide combinations for the oxygen evolution reaction [98].…”

Accelerated screening of Cu–Ga–Fe oxide semiconductors by combinatorial spray deposition and high-throughput analysis

“…8 Furthermore, it can be easily implemented as combinatorial deposition method for (1) thickness gradients by adjusting the covered area of multiple spray cycles [9][10][11][12][13][14][15] and (2) composition gradients a Energy Conversion and Hydrogen, Center for Energy, AIT Austrian Institute of by capitalizing the lateral spread of the spray cone and overlapping different precursor solutions consecutively 16 or simultanously. [17][18][19] Directly mixing multiple solutions during a laterally resolved coating process has already been reported. 20 In this contribution we synthesize combinatorial films with two-dimensional composition gradients of metal oxides.…”

“…8 Furthermore, it can be easily implemented as combinatorial deposition method for (1) thickness gradients by adjusting the covered area of multiple spray cycles 9–15 and (2) composition gradients by capitalizing the lateral spread of the spray cone and overlapping different precursor solutions consecutively 16 or simultanously. 17–19 Directly mixing multiple solutions during a laterally resolved coating process has already been reported. 20…”