Realizing Interfacial Electron/Hole Redistribution and Superhydrophilic Surface through Building Heterostructural 2 nm Co0.85 Se-NiSe Nanograins for Efficient Overall Water Splittings

A p-block dopant enables energy-efficient hydrogen production from biomass

Herein, we develop innovative p-block Bi-doped Co3O4 nanoflakes (Bi-Co3O4 NFAs) on nickel foam, which exhibit excellent electrocatalytic activity for both glucose oxidation (GOR) and H2 evolution reactions (HER). The two-electrode GOR-HER electrolyzer using Bi-Co3O4 NFAs as both the cathode and anode shows a remarkable reduced operation voltage of 1.48 V at 10 mA cm-2, superior to the 1.66 V of the OER-HER electrolyzer, demonstrating promising potential for advanced H2 production featuring energy saving and simultaneously produced value-added chemicals.

Single-atom platinum with asymmetric coordination environment on fully conjugated covalent organic framework for efficient electrocatalysis

Two-dimensional (2D) covalent organic frameworks (COFs) and their derivatives have been widely applied as electrocatalysts owing to their unique nanoscale pore configurations, stable periodic structures, abundant coordination sites and high surface area. This work aims to construct a non-thermodynamically stable Pt-N2 coordination active site by electrochemically modifying platinum (Pt) single atoms into a fully conjugated 2D COF as conductive agent-free and pyrolysis-free electrocatalyst for the hydrogen evolution reaction (HER). In addition to maximizing atomic utilization, single-atom catalysts with definite structures can be used to investigate catalytic mechanisms and structure-activity relationships. In this work, in-situ characterizations and theoretical calculations reveal that a nitrogen-rich graphene analogue COF not only exhibits a favorable metal-support effect for Pt, adjusting the binding energy between Pt sites to H* intermediates by forming unique Pt-N2 instead of the typical Pt-N4 coordination environment, but also enhances electron transport ability and structural stability, showing both conductivity and stability in acidic environments.

Double-Walled NiTeSe-NiSe2 Nanotubes Anode for Stable and High-Rate Sodium-Ion Batteries

Electrodes made of composites with heterogeneous structure hold great potential for boosting ionic and charge transfer and accelerating electrochemical reaction kinetics. Herein, hierarchical and porous double-walled NiTeSe-NiSe₂ nanotubes are synthesized by a hydrothermal process assisted in situ selenization. Impressively, the nanotubes have abundant pores and multiple active sites, which shorten the ion diffusion length, decrease Na⁺ diffusion barriers, and increase the capacitance contribution ratio of the material at a high rate. Consequently, the anode shows a satisfactory initial capacity (582.5 mA h g^-1 at 0.5 A g^-1 ), a high-rate capability, and long cycling stability (1400 cycles, 398.6 mAh g^-1 at 10 A g^-1 , 90.5% capacity retention). Moreover, the sodiation process of NiTeSe-NiSe₂ double-walled nanotubes and underlying mechanism of the enhanced performance are revealed by in situ and ex situ transmission electron microscopy and theoretical calculations.

In situ phosphoselenization induced heterointerface engineering endow NiSe2/Ni2P/FeSe2 hollow nanocages with efficient water oxidation electrocatalysis performance

Exploiting Earth-abundant and highly effective electrocatalysts toward the oxygen evolution reaction (OER) is critical for boosting water splitting efficiency. Herein, we proposed a novel in situ phosphoselenization strategy to fabricate heterostructured NiSe₂/Ni₂P/FeSe₂ (NiFePSe) nanocages with a modified electronic structure and well-defined nanointerfaces. Owing to the strong interfacial coupling and synergistic effect among the three components, the prepared NiFePSe nanocages exhibit superior OER performance with an ultralow overpotential of 242 mV at 10 mA cm^-2 and a small Tafel slope of 55.8 mV dec^-1 along with robust stability in 1 M KOH. Remarkably, the highly open 3D porous architecture, delicate internal voids, and numerous surface defects endow the NiFePSe nanocages with abundant active sites and enhanced electron mobility. In addition, the super-hydrophilic surface is conducive to facilitating mass transfer between the electrolyte and electrode and rapidly releasing the bubbles. This work may lead to new breakthroughs in the tuning of multi-component transition metal catalysts and the designing of highly active and durable materials for water splitting.

Facet Engineering of Advanced Electrocatalysts Toward Hydrogen/Oxygen Evolution Reactions

The crystal facets featured with facet-dependent physical and chemical properties can exhibit varied electrocatalytic activity toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) attributed to their anisotropy. The highly active exposed crystal facets enable increased mass activity of active sites, lower reaction energy barriers, and enhanced catalytic reaction rates for HER and OER. The formation mechanism and control strategy of the crystal facet, significant contributions as well as challenges and perspectives of facet-engineered catalysts for HER and OER are provided.

The electrocatalytic water splitting technology can generate high-purity hydrogen without emitting carbon dioxide, which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality. Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency. Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface. Owing to the anisotropy, crystal planes with different orientations usually feature facet-dependent physical and chemical properties, leading to differences in the adsorption energies of oxygen or hydrogen intermediates, and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this review, a brief introduction of the basic concepts, fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided. The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes. Subsequently, three strategies of selective capping agent, selective etching agent, and coordination modulation to tune crystal planes are comprehensively summarized. Then, we present an overview of significant contributions of facet-engineered catalysts toward HER, OER, and overall water splitting. In particular, we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity. Finally, the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.