Hexagonal boron nitride (hBN) is a two-dimensional material with exceptional chemical stability and environmental resistance, making it a critical candidate for applications in harsh conditions. Its structural similarity to graphene, often earning it the nickname "white graphene," belies its superior inertness to oxidation, acids, and thermal degradation. Unlike graphene, which oxidizes readily under ambient conditions, hBN remains stable even at elevated temperatures and in aggressive chemical environments. This stability stems from its unique bonding structure, where alternating boron and nitrogen atoms form a highly stable hexagonal lattice with strong covalent bonds and partial ionic character.

One of the most notable properties of hBN is its resistance to oxidation. While graphene begins to oxidize at temperatures around 300°C in air, forming defects and functional groups that degrade its electronic properties, hBN remains stable up to approximately 900°C. This high oxidation threshold is due to the strong B-N bonds, which require significant energy to break. Even at higher temperatures, hBN does not decompose but instead sublimes above 2700°C without melting, a property shared with few other materials. This makes hBN suitable for high-temperature applications such as crucibles for molten metals or protective barriers in extreme environments.

In addition to thermal stability, hBN exhibits remarkable resistance to acids and bases. Unlike graphene, which can be etched by strong oxidizers like nitric acid or sulfuric acid, hBN is largely unaffected by most corrosive chemicals. It shows negligible reactivity with hydrochloric acid, sulfuric acid, and even hydrofluoric acid at room temperature. Only under extreme conditions, such as molten hydroxides or highly concentrated acids at elevated temperatures, does hBN show signs of degradation. This chemical inertness makes it an ideal material for protective layers in chemical processing equipment or as a substrate for corrosive-environment electronics.

The stability of hBN also extends to its mechanical and electronic properties under environmental stress. Unlike transition metal dichalcogenides (TMDCs) such as MoS2, which can degrade in humid or oxidizing environments, hBN maintains its structural integrity. This resistance to hydrolysis and oxidation ensures long-term performance in electronic devices exposed to moisture or air. Furthermore, hBN's wide bandgap (~6 eV) prevents unwanted charge trapping or doping effects that plague narrower-bandgap 2D materials when exposed to environmental contaminants.

A key advantage of hBN over other 2D materials is its dielectric nature, which remains stable under electrical stress and high fields. Graphene, while highly conductive, suffers from electrochemical reactions at its edges or defects when subjected to high voltages or reactive species. In contrast, hBN's insulating properties prevent such degradation, making it a preferred choice for gate dielectrics or encapsulation layers in high-power electronics. Its thermal conductivity, comparable to that of graphene, further enhances its utility in dissipating heat without chemical breakdown.

The implications of hBN's stability are profound for harsh-environment applications. In aerospace, where materials face extreme temperature fluctuations and atomic oxygen exposure, hBN coatings or films can protect sensitive components without degrading. Similarly, in nuclear environments, where radiation resistance is critical, hBN's structural stability under ionizing radiation outperforms many conventional materials. Its inertness also benefits biomedical applications, where long-term implantation requires materials that resist biofouling and corrosion in physiological fluids.

Compared to other 2D materials, hBN's combination of thermal, chemical, and electrical stability is unmatched. Graphene, while mechanically robust, lacks the oxidation resistance needed for high-temperature applications. TMDCs, though versatile in optoelectronics, degrade under environmental stressors. Even diamond-like carbon coatings, known for their hardness, cannot match hBN's thermal stability in oxidizing atmospheres. This unique balance of properties positions hBN as a critical material for next-generation devices operating in extreme conditions.

Future research directions may explore the limits of hBN's stability under combined stressors, such as simultaneous exposure to high temperatures, radiation, and corrosive chemicals. Understanding defect formation mechanisms at atomic scales could further enhance its performance in real-world applications. As industries push the boundaries of material durability, hBN's inherent stability ensures its role as a cornerstone of advanced technologies in unforgiving environments.