[Paper Review] A durable and efficient electrocatalyst for saline water splitting with current density exceeding 2000 mA cm -2

Fengning Yang, Yuting Luo+8 more|arXiv (Cornell University)|Aug 30, 2021

Electrocatalysts for Energy Conversion1 references28 citations

TL;DR

The paper reports a Pt/Ni-Mo electrocatalyst anchored on a corrosion-resistant matrix that achieves 2000 mA cm-2 at an overpotential of 113 mV in saline-alkaline electrolyte and demonstrates durability across harsh conditions and scalable production.

ABSTRACT

Water electrolysis is promising for industrial hydrogen production to achieve a sustainable and green hydrogen economy, but the high cost of the technology limits its market share. Developing efficient yet economic electrocatalysts is crucial to decrease the cost of electricity and electrolytic cell. Meanwhile, electrolysis in seawater electrolyte can further reduce feedstock cost. Here we synthesize a type of electrocatalyst where trace precious metals are strongly anchored on corrosion-resistive matrix. As an example, the produced Pt/Ni-Mo electrocatalyst only needs an overpotential of 113 mV to reach an ultrahigh current density of 2000 mA cm-2 in saline-alkaline electrolyte, standing as the best performance so far. It shows high activity and long durability in various electrolytes and under harsh conditions, including strong alkaline and simulated seawater electrolytes, and under elevated temperatures up to 80 degree Celsius). This electrocatalyst is produced on a large scale at low cost and shows good performance in a commercial membrane electrode assembly stack, demonstrating its feasibility for practical water electrolysis

Motivation & Objective

• Develop a cost-effective, durable electrocatalyst for seawater or saline-alkaline electrolysis to reduce hydrogen production costs.
• Demonstrate ultrahigh current density performance (>2000 mA cm-2) with low overpotential.
• Show durability across various electrolytes, high temperature, and simulated seawater conditions.
• Validate scalability by large-scale production and performance in a membrane electrode assembly (MEA) stack.

Proposed method

• Synthesize a trace precious metal (Pt) anchored on a corrosion-resistant matrix (Ni-Mo) to create the Pt/Ni-Mo electrocatalyst.
• Measure electrochemical performance in saline-alkaline electrolyte to determine overpotential at 2000 mA cm-2.
• Characterize durability under harsh conditions including strong alkaline and simulated seawater electrolytes and temperatures up to 80 °C.
• Assess large-scale production feasibility and test in a commercial MEA stack to demonstrate practicality.

Experimental results

Research questions

• RQ1 Can a trace precious metal catalyst anchored on a corrosion-resistant matrix achieve ultrahigh current densities with low overpotential in saline-alkaline and simulated seawater electrolytes?
• RQ2 What is the durability and stability of Pt/Ni-Mo under harsh alkaline, elevated temperature, and seawater-like conditions?
• RQ3 Is the catalyst scalable for large-scale production and compatible with commercial MEA stacks?

Key findings

• Achieves 2000 mA cm-2 at an overpotential of 113 mV in saline-alkaline electrolyte.
• Demonstrates high activity and long durability across various electrolytes and harsh conditions, including simulated seawater and up to 80 °C.
• Can be produced on a large scale at low cost and functions in a commercial MEA stack, indicating practical feasibility.