Author Information:

1. First author:

Wang Shenghua, PhD student, School of Materials Science and Engineering, Zhejiang University.

2. Corresponding author:

1) Prof. Wei Sun, Academician Yang Deren, State Key Laboratory of Silicon Materials, Zhejiang University

2) Professor Geoffrey Ozin, University of Toronto, Canada

About the article:

Using various catalytic means to convert CO2 into high value-added products can theoretically effectively deal with the environmental problems caused by excessive CO2 emissions and the energy shortage caused by the massive combustion of fossil fuels. However, at present, the driving energy of catalytic reaction is mainly from the combustion of fossil energy, which is a process that releases CO2. So here comes a question: can the use of catalysis really achieve negative CO2 emission?

In this paper, we discuss the CO2 footprint of photothermal catalysis and traditional thermal catalysis, taking the reverse water gas and Sabatier reaction in batch kettle and mobile phase reactor as examples. Here are the main points:

1) Several factors affecting the net CO2 emission rate are summarized: the amount of CO2 emitted by producing 1 kWh of electricity; CO2 emissions per mole of H2 production; CO2 conversion rate; The electrical power consumption of each device in the catalytic reaction. These factors are correlated with the net CO2 emission, and some general formulae are proposed, which can be used to evaluate the net CO2 emission rate of each individual system.

2) The net emission rate of CO2 in thermal catalysis and photothermal catalysis is deduced by taking several factors in 1) as variables respectively, and several ways to reduce CO2 emission are proposed: (1) To develop and upgrade the power production system to reduce CO2 emission in the power generation process; (2) the development of energy-saving equipment; (3) Optimize the reactor layout; (4) Design and preparation of high-performance catalysts;

3) Taking the laboratory scale reaction system as an example, it is found that for batch reactor, only when the power of xenon lamp source is less than 0.12kW, the net CO2 emission through photothermal pathway is smaller than that of thermal catalysis. Under the premise of reasonable equipment assembly and configuration, the use of sunlight or clean energy can achieve zero CO2 emission when the CO2 conversion rate reaches 1mol·g−1·h−1. When the ether sunlight is used as the light source, the mobile phase reactor seems to have more advantages than the batch reactor. Zero CO2 emission can be achieved only when the CO2 conversion rate reaches 0.176 mol·g−1·h−1. However, achieving this rate while achieving high CO2 conversion rates is difficult. It is worth noting that this paper proposes an ideal way to lead to negative CO2 emission: when the sun is chosen as the light source and hydrogen production is from renewable energy, negative CO2 emission can always be achieved through photothermal catalysis with mobile phase reactor as the medium.

It is believed that some general formulae and prospects presented in this paper will have a certain enlightening effect on the future development of photothermal catalytic CO2 reduction. DOI :10.1002/smll.202007025, link to original article：https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202007025

Instruments used in this article:

Product name: miniature photothermal catalytic micro-reaction system

Product model: CEL-GPPCM

Product name: photocatalytic reaction kettle

Product model: CEL-HPR100