According to Hebei Messi Biology, in our daily lives, white sugar is a symbol of sweetness that graces our taste buds, while magnesium oxide—a white powder commonly found in antacids or industrial additives—seems ordinary and unremarkable. However, in scientists’ laboratories, when “sugar” is converted into “carbon” through high-temperature treatment and then encounters “magnesium oxide,” a fascinating chemical reaction quietly unfolds in the microscopic world. The combination of these two is not merely a simple mixture, but rather a master key leading to high-performance advanced materials.
First, we need to understand what “sugar-derived carbon” (sugar carbon) is. When carbohydrate substances such as sucrose and glucose undergo thermal pyrolysis at high temperatures, the black porous solid left behind after moisture evaporation is sugar-derived carbon. It is essentially a carbon material. Although it is carbon just like diamond or graphite, it is neither dazzling like a diamond nor smooth for writing like graphite; instead, it is a relatively structurally disordered carbon precursor rich in micropores. While this material itself possesses good adsorption properties, against the backdrop of modern technology’s extremely high demands for material precision, pure sugar-derived carbon often falls short, as its pore size distribution is uneven and its electrical conductivity needs improvement. At this point, magnesium oxide (MgO) steps into the spotlight. During the preparation of sugar-derived carbon, magnesium oxide plays the crucial role of a “pore-maker” or “template”.
Imagine we want to build a labyrinth with countless rooms of specific sizes (i.e., porous carbon materials). If we were just randomly stacking bricks (sugar carbonization), the size and shape of the rooms would be chaotic. However, magnesium oxide particles act like countless precise molds pre-placed at the construction site. Scientists evenly mix sugar solutions with nano-sized magnesium oxide powder, much like pouring syrup into the gaps between magnesium oxide particles. During high-temperature carbonization, the sugar gradually turns into carbon, tightly enveloping the surface and surrounding areas of the magnesium oxide particles.
The most magical step happens last: after carbonization is complete, scientists use an acidic solution (such as hydrochloric acid) for washing. Magnesium oxide is a basic oxide that readily reacts with acid and dissolves. Consequently, the magnesium oxide acting as the “mold” disappears, leaving behind only the space it previously occupied. In this way, pores shaped like the magnesium oxide particles are replicated inside the originally solid carbon block. This technique is known as the “hard template method”. By controlling the size and shape of the magnesium oxide particles, scientists can precisely “customize” the pore structure of the sugar-derived carbon. This is akin to playing with plasticine: placing a building block of a specific shape in the middle, and once the block is removed, leaving a perfect impression on the clay.
So, what is this magnesium oxide-“sculpted” sugar-derived carbon actually used for? The answer is: a wide range of applications. Because of its huge specific surface area and controllable pore size, this material serves as an ideal electrode material for supercapacitors. As a new type of energy storage device, supercapacitors require electrode materials to instantly adsorb a large amount of charge like a sponge, and the magnesium oxide-templated sugar-derived carbon meets this exact demand, allowing electric vehicles to run faster and charge faster. Furthermore, in the field of environmental remediation, this modified sugar-derived carbon is also an “adsorption expert”. It can efficiently capture heavy metal ions in water or harmful gases in the air, acting as an environmental “purifier”.
The combination of sugar-derived carbon and magnesium oxide is a vivid example of “the ordinary creating the extraordinary” in materials science. Sweet sugar and modest magnesium oxide, through the baptism of high temperature and chemistry, are reborn, transforming into dark horse materials that drive modern technology. This is precisely the charm of science—establishing unexpected connections between seemingly unrelated things to create infinite possibilities for human life.