Biomaterials are in use for the replacement and reconstruction of several tissues and organs as treatment and enhancement. Metallic, organic, and composites are some of the common materials currently in practice. Metallic materials contribute a big share of their mechanical strength and resistance to corrosion properties, while organic polymeric materials stand high due to their biocompatibility, biodegradability, and natural availability. To enhance the biocompatibility of these metals and alloys, coatings are frequently applied. Organic polymeric materials and ceramics are extensively utilized for this purpose due to their outstanding characteristics of biocompatibility and biodegradability. Hydroxyapatite (HAp) is the material from the ceramic class which is an ultimate candidate for coating on these metals for biomedical applications. HAp possesses similar chemical and structural characteristics to normal human bone. Due to the bioactivity and biocompatibility of HAp, it is used for bone implants for regenerating bone tissues. This review covers an extensive study of the development of HAp coatings specifically for the orthopaedic applications that include different coating techniques and the process parameters of these coating techniques. Additionally, the future direction and challenges have been also discussed briefly in this review, including the coating of HAp in combination with other calcium magnesium phosphates that occur naturally in human bone.

The development of dual‐functional materials for sustainable environmental remediation and electrochemical energy conversion remains an important research area. In this work, g‐C ₃ N ₅ (CN), 1% Ag‐modified CN (ACN), cadmium sulfide (CdS), 20% CN/CdS (CCN), and 20% (1% ACN)/CdS (CACN) were synthesized via calcination and hydrothermal methods. Among them, CACN exhibited the highest photocatalytic performance, achieving 97% removal of norfloxacin (NOR) within 70 min under white LED irradiation, with a rate constant 3.45 times higher than that of pristine CdS. The composite also maintained stable performance over five consecutive cycles. Radical‐scavenging and electron spin resonance (ESR) analyses indicated that superoxide radicals (O ₂ ^•− ) and hydroxyl radicals (OH ^• ) were the dominant reactive species involved in NOR degradation. High‐performance liquid chromatography–mass spectrometry (HPLC–MS) analysis identified degradation intermediates and proposed possible transformation pathways. UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), Mott–Schottky analysis (MS), and density functional theory (DFT) calculations supported the formation of a Z‐scheme charge–transfer mechanism. The Ag incorporations likely improved charge separation through localized surface plasmon resonance (LSPR) effects and the formation of Ohmic contacts. Furthermore, electrochemical evaluation showed that CACN supported on Ni foam exhibits enhanced hydrogen evolution reaction (HER) performance, delivering an overpotential ( η ) of 111 mV at 10 mA/cm ² in 1 M KOH, with stable performance over 20 h. These findings demonstrate that CACN is a promising dual‐functional material for antibiotic degradation and hydrogen production.

Adsorption‐based iodine capture offers an effective strategy for managing radioactive nuclear waste. In this study, a carboxylic acid–functionalized covalent organic framework (COF─COOH) was synthesized via a multicomponent Doebner reaction and postsynthetically modified with aqueous ammonia to produce an ionic framework, [COF─COO ⁻ ][NH ₄ ] ⁺ . A nonfunctionalized analog, COF─TpTta, was also synthesized for comparison. Iodine vapor uptake at 75°C followed the order [COF─COO ⁻ ][NH ₄ ] ⁺ (2.4 ± 0.092 g/g) > COF─COOH (1.8 ± 0.07 g/g) > COF─TpTta (1.5 ± 0.082 g/g). Spectroscopic analyses revealed that COF─TpTta and COF─COOH primarily captured iodine via charge–transfer interactions, whereas [COF─COO ⁻ ][NH ₄ ] ⁺ utilized an additional electrostatic and hydrogen bonding mechanism between iodine species and ammonium carboxylate groups. This dual‐binding mechanism enhanced iodine uptake by 60% over COF─TpTta despite reduced surface area, pore size, and pore volume. [COF─COO ⁻ ][NH ₄ ] ⁺ retained over 80% of its gaseous phase iodine adsorption capacity after four cycles, maintained iodine loading over 30 h, and exhibited high iodine uptake (225 ± 16.76 mg/g) from n‐hexane following Langmuir‐type adsorption. These results demonstrate that tailored binding‐site chemistry, rather than solely textural optimization, can drives superior iodine capture. This ionic COF design strategy offers a versatile and robust platform for synthesizing next‐generation radioiodine adsorbents.