19 Jul 2012

An Introduction to Electrocatalysis: Hydrogen Evolution from Mono and Binuclear Cobalt Complexes

Literature Discussion

Submitted by Abby O'Connor, The College of New Jersey
Categories
Description: 

This learning object was developed at the 2012 NSF sponsored cCWCS VIPEr workshop at UNC-CH where we were fortunate to hear Jillian Dempsey present this research that has appeal to students. This work focuses on an exciting and promising strategy to develop new technology to support a solar energy economy. This literature discussion leads students through a current application in the field of electrocatalysis. The primary literature article for the discussion is found in Proc. Natl. Acad. Sci. USA 2012 109 (39) 15560-15564.

Learning Goals: 

Students should be able to:

- identify the chemical reaction presented and balance the half reactions for water splitting

- explain the role of a catalyst in an electrochemical reaction

- propose and evaluate the validity of possible mechanisms based on the experimental data

- find and rationalize trends in the series of catalysts presented in the article

- identify the features associated with electrocatalysis

Implementation Notes: 

The intent of this literature discussion is geared to provide a broad introduction to the field of electrocatalysis.

Two implementation strategies we thought of are:

  1. Have the students read the article, answer questions 1-4, and watch Chip Nataro’s 5-slides about cyclic voltammetry. In class, discuss questions 5 and 6. For a more in depth discussion, assign questions 7-11.
  2. Have the students read the article and watch Chip Nataro’s 5-slides about cyclic voltammetry the night before. Discuss questions 1-4 in class and assign the questions 5 and 6 for homework.


For a more in depth discussion on electrocatalysis we included a more challenging questions in our document (7-11). These questions could also be used on exams.

Time Required: 
1 class period
Evaluation
Evaluation Methods: 

Collect responses to questions not covered in class.

Grade class participation.

Assign a more in depth question on an exam. 

Creative Commons License: 
Creative Commons Licence

Comments

Since I helped to create this LO, I felt obliged to try it out in my class. I had the students look at Chip's Echem slides, read the article, and answer 7 questions and upload them to me the night for the in class discussion. All students completed the assignment. I used this as an introduction to catalysis. I talked about catalysis and different types of catalysts which lead nicely into electrocatalysis. The average for the question was 42/50 and I had 40 points for the questions and 10 points for class participation. About 80% of the class participated in the discussion. 

I was surprised by the handful of students that did not recognize that DG for water splitting would not change when a catalyst was added. I asked the same question on my final and a few students still did not answer this correctly. 

Most students successfully counted the electrons but few recognized why this may be ok for this system (when the 18-e rule may not apply). For the mechanism question, I would suggest adding mention that you want the students to draw the reactions for this cobalt system and they can omit the ligand for simplicity. Many students just draw out the H2 reaction.

The students did not recognize the purpose of the experiment about how the data helped to support the heterolytic method. I asked questions on my final related to this and most students got them wrong even after the in class discussion. If I do this assignment again I will make sure the students evaluate this before class so they understand the point of the article.

In class, I asked questions 8, 9, and 11 (original posting) to faciliate discussion.

I am attaching the document I used. 

I also found that in our key we are missing the 2H+ to balance the equation. 

The article is now in print and the citation is: Proc. Natl. Acad. Sci. USA 2012 109 (39) 15560-15564.

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