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Title: Efficient electrochemical CO2 conversion powered by renewable energy

Here, the catalytic conversion of CO2 into industrially relevant chemicals is one strategy for mitigating greenhouse gas emissions. Along these lines, electrochemical CO2 conversion technologies are attractive because they can operate with high reaction rates at ambient conditions. However, electrochemical systems require electricity, and CO2 conversion processes must integrate with carbon-free, renewable-energy sources to be viable on larger scales. We utilize Au25 nanoclusters as renewably powered CO2 conversion electrocatalysts with CO2 → CO reaction rates between 400 and 800 L of CO2 per gram of catalytic metal per hour and product selectivities between 80 and 95%. These performance metrics correspond to conversion rates approaching 0.8–1.6 kg of CO2 per gram of catalytic metal per hour. We also present data showing CO2 conversion rates and product selectivity strongly depend on catalyst loading. Optimized systems demonstrate stable operation and reaction turnover numbers (TONs) approaching 6 × 106 mol CO2 molcatalyst–1 during a multiday (36 hours total hours) CO2electrolysis experiment containing multiple start/stop cycles. TONs between 1 × 106 and 4 × 106 molCO2 molcatalyst–1 were obtained when our system was powered by consumer-grade renewable-energy sources. Daytime photovoltaic-powered CO2 conversion was demonstrated for 12 h and we mimicked low-light or nighttime operation formore » 24 h with a solar-rechargeable battery. This proof-of-principle study provides some of the initial performance data necessary for assessing the scalability and technical viability of electrochemical CO2 conversion technologies. Specifically, we show the following: (1) all electrochemical CO2 conversion systems will produce a net increase in CO2 emissions if they do not integrate with renewable-energy sources, (2) catalyst loading vs activity trends can be used to tune process rates and product distributions, and (3) state-of-the-art renewable-energy technologies are sufficient to power larger-scale, tonne per day CO2 conversion systems.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2]
  1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
  2. Carnegie Mellon Univ., Pittsburgh, PA (United States)
Publication Date:
OSTI Identifier:
1240139
Report Number(s):
NETL-PUB--1221
Journal ID: ISSN 1944-8244
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 7; Journal Issue: 28; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society
Research Org:
National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION electrocatalysis; CO2 conversion; gold nanomaterials; renewable energy; catalysis; environmental