A Different Kind of Rice Cooker

In the early days of September, Haotian Wang, an engineer at Rice University in Houston, Texas, was able to create a catalytic reactor that converts carbon dioxide into usable fuel. The reactor uses a modified electrolyzer to trigger the reduction of carbon dioxide and host a reaction that effectively produces formic acid fuel (CH2O2). The invention was successful due to two key innovations: the catalytic element bismuth and the solid electrolyte. The development of the machine opens a door to a future in which large-scale fuel reactors lessen the rate at which greenhouse gases are released into the atmosphere.

According to the news article released by Rice University, the electrolyzer implements “a catalyst that selects for carbon dioxide and reduces it to a negatively charged formate, which is pulled through a gas diffusion layer (GDL) and the anion exchange membrane (AEM) into the central [solid] electrolyte. [… On the other side,] an oxygen evolution reaction (OER) catalyst generates positive protons from water and sends them through the cation exchange membrane (CEM). The ions recombine into formic acid or other products that are carried out of the system by deionized (DI) water and gas.”

To put that complicated passage in simple terms: the chemical process which drives this reactor allows for the production of fuel from a primary source of energy, which could include wind and solar power.

The reaction cycle of the reactor is cheaper to run since its electrolyzer manages to shorten the reaction time with bismuth atoms and eliminate the need for salts with its new solid electrolyte mechanisms. Chuan Xia, a graduate researcher from Rice University, emphasizes how the invention of the catalytic bismuth allows for a more reliable catalytic reaction within the electrolyzer. This in part is due to the element’s substantial weight, allowing for a stronger, longer-lasting catalyst for the reactor. Creating bismuth also helps lower production costs, since Xia’s team “developed a way to produce [bismuth] at the kilogram scale. That [would] make [their] process easier to scale up for the industry.” With a more abundant supply of bismuth for a better price, the scientists of the project can invest more time and research into developing the reactor further.

The solidified electrolyte at the center of the entire process also makes the reactor far more efficient than it would otherwise be. According to the Nature Energy research article produced by Xia and the team, reducing carbon dioxide production in the past was commonly achieved by using liquid electrolytes with salt solutions for better ion movement. However, this created the opportunity for the formic acid produced to contain salts from the liquid electrolytes’ solutions, which resulted in the additional, expensive step of separating the salts from the formic acid for use as a fuel. Instead, through the use of electrolytes in their solid forms, “electrochemically generated cations (such as H+) and anions (such as HCOO-) are combined to form pure product solutions without mixing with other ions … [showing] 100 h continuous and stable generation of 0.1 M HCOOH with negligible degradation in selectivity and activity.” This exemplifies the efficiency of solidified electrolytes and shows how using them allows for a more accessible way for researchers to study and produce fuels such as formic acid.

Rice University’s reactor represents a step toward a plausible future in which the rate of greenhouse gases being released into the air is substantially decreased. In the article about the reactor, Wang states that this is possible by creating an endless cycle of clean energy consumption to power the conversion of carbon dioxide from the atmosphere and other locations into formic acid fuel. The fuel then would be used up, releasing carbon dioxide back into the atmosphere only to be converted back into fuel again. The cycle would essentially flatten the increasing rate of carbon dioxide being released into the atmosphere, therefore slowing down the rate of global warming and climate change. While the article states that “the new electrocatalyst reached an energy conversion efficiency of about 42 percent,” the increasing effectiveness and innovation of the reactor demonstrates a need for further research to expand the reactor’s potential impact. With future improvements, the reactor could act as a significant, long-term step toward the solution to global warming throughout the world.