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Elastomers generally possess low Young's modulus and high failure strain, which are widely used in soft robots and intelligent actuators. However, elastomers generally lack diverse functionalities, such as stimulated shape morphing, and a general strategy to implement these functionalities into elastomers is still challenging. Here, a microfluidic 3D droplet printing platform is developed to design composite elastomers architected with arrays of functional droplets. Functional droplets with controlled size, composition, position, and pattern are designed and implemented in the composite elastomers, imparting functional performances to the systems. The composited elastomers are sensitive to stimuli, such as solvent, temperature, and light, and are able to demonstrate multishape (bow‐ and S‐shaped), multimode (gradual and sudden), and multistep (one‐ and two‐step) deformations. Based on the unique properties of droplet‐embedded composite elastomers, a variety of stimuli‐responsive systems are developed, including designable numbers, biomimetic flowers, and soft robots, and a series of functional performances are achieved, presenting a facile platform to impart diverse functionalities into composite elastomers by microfluidic 3D droplet printing.

Transition metal‐nitrogen‐carbon materials with atomically dispersed active sites are promising catalysts for oxygen evolution reaction (OER) since they combine the strengths of both homogeneous and heterogeneous catalysts. However, the canonically symmetric active site usually exhibits poor OER intrinsic activity due to its excessively strong or weak oxygen species adsorption. Here, a catalyst with asymmetric MN₄sites based on the 3‐s‐triazine of g‐C₃N₄(termed as a‐MN₄@NC) is proposed. Compared to symmetric, the asymmetric active sites directly modulate the oxygen species adsorption via unifying planar and axial orbitals (dx²‐y², dz²), thus enabling higher OER intrinsic activity. In Silico screening suggested that cobalt has the best OER activity among familiar nonprecious transition metal. These experimental results suggest that the intrinsic activity of asymmetric active sites (179 mV overpotential at onset potential) is enhanced by 48.4% compared to symmetric under similar conditions. Remarkably, a‐CoN₄@NC showed excellent activity in alkaline water electrolyzer (AWE) device as OER catalyst, the electrolyzer only required 1.7 V and 2.1 V respectively to reach the current density of 150 mA cm⁻²and 500 mA cm⁻². This work opens an avenue for modulating the active sites to obtain high intrinsic electrocatalytic performance including, but not limited to, OER.