Electrocatalytic water splitting using renewable energy is widely considered as a clean and sustainable way to produce hydrogen as an ideal energy fuel for the future. Electrocatalysts are indispensable elements for large‐scale water electrolysis, which can efficiently accelerate electrochemical reactions occurring at both ends. Benefitting from high specific surface area, well‐defined void space, and tunable chemical compositions, hollow nanostructures can be applied as promising candidates of direct electrocatalysts or supports for loading internal or external electrocatalysts. Herein, some recent progress in the structural design of micro‐/nanostructured hollow materials as advanced electrocatalysts for water splitting is summarized. First, the design principles and corresponding strategies toward highly effective hollow electrocatalysts for oxygen/hydrogen evolution reactions are highlighted. Afterward, an overview of current reports about hollow electrocatalysts with diverse architectural designs and functionalities is given, including direct hollow electrocatalysts with single‐shelled, multi‐shelled, or open features and heterostructured electrocatalysts based on hollow hosts. Finally, some future research directions of hollow electrocatalysts for water splitting are discussed based on personal perspectives.

The growth of lithium (Li) dendrites and the huge volume change are the critical issues for the practical applications of Li‐metal anodes. In this work, a spatial control strategy is proposed to address the above challenges using lotus‐root‐like Ni–Co hollow prisms@carbon fibers (NCH@CFs) as the host. The homogeneously distributed bimetallic Ni–Co particles on the N‐doped carbon fibers serve as nucleation sites to effectively reduce the overpotential for Li nucleation. Furthermore, the 3D conductive network can alter the electric field. More importantly, the hierarchical lotus‐root‐like hollow fibers provide sufficient void space to withstand the volume expansion during Li deposition. These structural features guide the uniform Li nucleation and non‐dendritic growth. As a result, the NCH@CFs host enables a very stable Li metal anode with a low voltage hysteresis during repeated Li plating/stripping for 1200 h at a current density of 1 mA cm−2.

Serious challenges in energy and the environment require us to find solutions that use sustainable processes. There are many sustainable electrocatalytic processes that might provide the answers to the above-mentioned challenges, such as the oxygen reduction reaction (ORR), water splitting, the carbon dioxide reduction reaction (CO2RR), and the nitrogen reduction reaction (NRR). These reactions can enhance the value added by producing hydrogen energy through water splitting or convert useless CO2 and N2 into fuels and NH3. These electrocatalytic reactions can be driven by high-performance catalysts. Therefore, the exploration of novel electrocatalysts is one of the important electrocatalytic fields. In this paper, we aim to systematically discuss a variety of electrocatalysts used for sustainable processes and to give further insights into their status and associated challenges. We invited many famous research groups to write this roadmap with topics including platinum (Pt) and its alloys for ORR, oxides for ORR, chalcogenides for ORR, carbon-based hollow electrocatalysts for ORR, carbides for ORR, atomically dispersed Fe–N–C catalysts for ORR, metal-free catalysts for ORR, single-atom catalysts (SACs) for ORR, metal boride (MB) electrocatalysts for water splitting, transitional metal carbides (TMCs) for water splitting, transition metal (TM) phosphides for water splitting, oxides for water splitting, sulfides for water splitting, layered double hydroxides for water splitting, carbon-based electrocatalysts for water splitting, Ru-based electrocatalysts for water splitting, metal oxides for CO2RR, metal sulfides for CO2RR, metals for CO2RR, carbon for CO2RR, SACs for CO2RR, heterogeneous molecular catalysts for CO2RR, oxides for NRR, chalcogenides for NRR, C3N4 for NRR, SACs for NRR, etc. Their contributions enabled us to compile this 2020 roadmap on electrocatalysts for green catalytic processes and provide some suggestions for future researchers.

Electrochemical water splitting processes including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are considered as one of the most promising methods for high-purity hydrogen production. Ni-Fe based compounds,...

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