Global water bodies are increasingly imperiled by nitrate pollution, primarily originating from industrial waste, agricultural runoffs, and urban sewage. This escalating environmental crisis challenges traditional water treatment paradigms and necessitates innovative solutions. Electro-catalysis, especially utilizing copper-based catalysts, known for their efficiency, cost-effectiveness, and eco-friendliness, offer a promising avenue for the electro-catalytic reduction of nitrate to ammonia. In this review, we systematically consolidate current research on diverse copper-based catalysts, including pure Cu, Cu alloys, oxides, single-atom entities, and composites. Furthermore, we assess their catalytic performance, operational mechanisms, and future research directions to find effective, long-term solutions to water purification and ammonia synthesis. Electro-catalysis technology shows the potential in mitigating nitrate pollution and has strategic importance in sustainable environmental management. As to the application, challenges regarding complexity of the real water, the scale-up of the commerical catalysts, and the efficient collection of produced NH₃ are still exist. Following reseraches of catalyst specially on long term stability and in situ mechanisms are proposed.

Direct ink writing (DIW) has recently emerged as an appealing method for designing and fabricating three-dimensional (3D) objects. Complex 3D structures can be built layer-by-layer via digitally controlled extrusion and deposition of aqueous-based colloidal pastes. The formulation of well-dispersed suspensions with specific rheological behaviors is a prerequisite for the use of this route. In this review article, the fundamental concepts of DIW are presented, including the operation principles and basic features. Typical strategies used for ink formulation are discussed with a focus on the most widely used electrode materials, including graphene, Mxenes, and carbon nanotubes. The recent progress in printing design of emerging energy storage systems, encompassing rechargeable batteries, supercapacitors, and hybrid capacitors, is summarized. Challenges and future perspectives are also covered to provide guidance for the future development of DIW.