New Material For Cheaper and More Efficient Fuel-Cells

Fuel cell technology has come a long way since the early days in the Apollo space program, but it is still a rather expensive module, limiting its wider application. A major reason are the platinum (Pt) catalysts used in most designs, which are costly and insufficient for industry demand.

As a possible solution for this, a new material which is both cheaper to make and better performing is now being developed by a research team of Ulsan National Institute of Science and Technology (UNIST) in South Korea, Case Western Reserve University and University of North Texas. A news release about first successful tests of the new material says it could "pave a new way for affordable commercialization of fuel cells with efficient metal-free electrocatalysts using edge-halogenated graphene nanoplatelets.

Beside the high cost of platinum, another major drawback for commercialization of fuel cell technology is the sluggish oxygen reduction reaction (ORR) at cathode. Although, Pt and its alloys have been considered to be the most reliable cathodic ORR electrocatalysts in fuel cells, it also suffers from methanol crossover/carbon monoxide (CO) poisoning effects and poor long-term operation stability.

Now, there is an alternative. The researchers have created a low cost metal-free catalyst which they believe can be scaled up for industrial and commercial use. They synthesized a series of edge-selectively halogenated (Cl, Br and I) graphene nanoplatelets (XGnPs) by ball-milling graphite flake in the presence of chlorine (Cl2), bromine (Br2), or iodine (I2), respectively.

The resultant XGnPs were tested as cathode electrodes of fuel cells and revealed remarkable electrocatalytic activities for ORR with higher tolerance to methanol crossover/CO poisoning effects and longer-term stability than those of the original graphite and commercial Pt/C electrocatalysts. This makes XGnPs a possible replacement for platinum (Pt) in fuel cells, bringing down the cost and increasing the likelihood of commercialization.

"Our result presents new insights and practical methods for designing edge-functionalized GnPs as high-performance metal-free ORR electrocatalysts through low-cost and scalable ball-milling techniques," said Prof. Jong-Beom Baek of Ulsan National Institute of Science and Technology, who led the research team.

"We made metal-free catalysts using an affordable and scalable process," said Prof. Liming Dai of Case Western Reserve and one of the paper's authors. "The catalysts are more stable than platinum catalysts and tolerate carbon monoxide poisoning and methanol crossover."

The research was led by Prof. Jong-Beom Baek, director of the Interdisciplinary School of Green Energy/Low-Dimensional Carbon Materials Center at South Korea's Ulsan National Institute of Science and Technology. Fellow authors include: In-Yup Jeon, Hyun-Jung Choi, Min Choi, Jeong-Min Seo, Sun-Min Jung, Min-Jung Kim and Neojung Park, from Ulsan; Sheng Zhang from Case Western Reserve; and Lipeng Zhang and Zhenhai Xia from North Texas. (Source: UNIST)