Production of functionally graded materials (FGMs, i.e., a gradual transition from one material to another) and components is challenging using conventional manufacturing techniques. Additive manufacturing (AM) provides a new opportunity for producing FGMs. However, current metal AM technologies including powder-bed fusion are limited to producing single material components or vertical FGM parts, i.e., a different material composition in different layers but not within the same layer, and in situ changing materials is challenging. In this paper, we demonstrate the fabrication of horizontal and 3D 316L/Cu10Sn components with FGM within the same layer and in different layers, via a proprietary multiple selective powder delivery array device incorporated into a selective laser melting system that allowed the deposition of up to six different materials point by point. The manufactured component macrostructure, microstructure, microhardness, and phases were examined. Smooth transition from one material to the other was realized. Also, an interesting phenomenon was found that the maximum hardness was at 50% 316L and 50% Cu10Sn. The work would open up a new opportunity for the manufacturing of true 3D functionally graded components using additive manufacturing and for the rapid development of new metal alloy systems.

Single-atom catalysts (SACs) with atomically dispersed catalytic sites have shown outstanding catalytic performance in a variety of reactions. However, the development of facile and high-yield techniques for the fabrication of SACs remains challenging. In this paper, we report a laser-induced solid-phase strategy for the synthesis of Pt SACs on graphene support. Simply by rapid laser scanning/irradiation of a freeze-dried electrochemical graphene oxide (EGO) film loaded with chloroplatinic acid (H₂PtCl₆), we enabled simultaneous pyrolysis of H₂PtCl₆ into SACs and reduction/graphitization of EGO into graphene. The rapid freezing of EGO hydrogel film infused with H₂PtCl₆ solution in liquid nitrogen and the subsequent ice sublimation by freeze-drying were essential to achieve the atomically dispersed Pt. Nanosecond pulsed infrared (IR; 1064 nm) and picosecond pulsed ultraviolet (UV; 355 nm) lasers were used to investigate the effects of laser wavelength and pulse duration on the SACs formation mechanism. The atomically dispersed Pt on graphene support exhibited a small overpotential of −42.3 mV at −10 mA cm⁻² for hydrogen evolution reaction and a mass activity tenfold higher than that of the commercial Pt/C catalyst. This method is simple, fast and potentially versatile, and scalable for the mass production of SACs.

Rapid synthesis of high-entropy alloy nanoparticles (HEA NPs) offers new opportunities to develop functional materials in widespread applications. Although some methods have successfully produced HEA NPs, these methods generally require rigorous conditions such as high pressure, high temperature, restricted atmosphere, and limited substrates, which impede practical viability. In this work, we report laser solid-phase synthesis of CrMnFeCoNi nanoparticles by laser irradiation of mixed metal precursors on a laser-induced graphene (LIG) support with a 3D porous structure. The CrMnFeCoNi nanoparticles are embraced by several graphene layers, forming graphene shell-encapsulated HEA nanoparticles. The mechanisms of the laser solid-phase synthesis of HEA NPs on LIG supports are investigated through theoretical simulation and experimental observations, in consideration of mixed metal precursor adsorption, thermal decomposition, reduction through electrons from laser-induced thermionic emission, and liquid beads splitting. The production rate reaches up to 30 g/h under the current laser setup. The laser-synthesized graphene shell-encapsulated CrMnFeCoNi NPs loaded on LIG-coated carbon paper are used directly as 3D binder-free integrated electrodes and exhibited excellent electrocatalytic activity towards oxygen evolution reaction with an overpotential of 293 mV at the current density of 10 mA/cm² and exceptional stability over 428 h in alkaline media, outperforming the commercial RuO₂ catalyst and the relevant catalysts reported by other methods. This work also demonstrates the versatility of this technique through the successful synthesis of CrMnFeCoNi oxide, sulfide, and phosphide nanoparticles.