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Regulating the electronic structure of Bi-based materials by alloying engineering is promising to promote the electrocatalytic activity, but it remains some challenges to be solved. In this study, a facile electrochemical co-deposition strategy is developed to synthesize the bimetallic Bi9Cu1 alloy nanosheet on carbon cloth (Bi9Cu1/CC), which represents a novel self-supporting electrode for the electrocatalytic carbon dioxide (CO2) reduction reaction (CO2RR). The Bi9Cu1/CC catalyst has achieved a remarkable catalytic performance with high Faradaic efficiencies (FE) of over 90% for formate at wide potentials from −0.7 to −1.2 V vs. reversible hydrogen electrode (RHE). Moreover, the reversible Zn-CO2 battery can be driven by Bi9Cu1/CC cathode with a largest power density of 1.4 mW·cm−2, and superior operating stability. The systematic characterizations and electrochemical results confirm that the improved catalytic active sites, the enhanced mass/charge transport and the optimal reaction kinetics of Bi nanosheet are realized for CO2RR by Cu alloying. In situ attenuated total reflection infrared (ATR-IR) result confirms the bimetallic Bi-Cu active sites prefer to follow the ⋆OCHO conversion pathway. The density functional theory (DFT) calculations suggest that the Cu alloying contributes to the increased density of states near the Fermi surface of Bi and the optimized adsorption of ⋆OCHO intermediates on the Bi sites, resulting in the excellent catalytic performance. [ABSTRACT FROM AUTHOR]

Tuning coordination environment of single‐atom catalysts (SACs) is widely applied for the electrochemical CO2 reduction reaction (CO2RR). However, the influence of the interaction between SACs and support on the catalytic performance are not comprehensive. Herein, taking cobalt phthalocyanine (CoPc) as a conceptual example, a hetero S‐atom doping strategy of hollow carbon sphere (S‐NHC) is put forward as a carrier, revealing the intrinsic relationship between microenvironment regulation and catalytic activity of single Co‐atom. The additional S doping may induce more carbon defect and increases the content of pyrrolic N in the S‐NHC sample, leading to stronger electronic interaction of heterogeneous CoPc/S‐NHC for boosting CO2RR performance. Remarkably, the catalyst achieves a highest CO selectivity of nearly 100% at −0.6 V, and the FECO are over 90% in a wide potential range from −0.4 to −0.8 V in a flow cell. The maximum power density is high as 2.68 mW cm−2 at 4.7 mA cm−2 for the Zn–CO2 battery with CoPc/S‐NHC cathode. In situ attenuated total reflection infrared (ATR‐IR) spectroscopy reveals the formation of key *COOH and *CO intermediates, while the calculation result confirm the optimized Gibbs free energy of these intermediates on CoPc/S‐NHC, suggesting the feasibility of the regulation strategy. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of carbon dioxide (ERCO2) to formate with high selectivity has been considered a promising strategy to overcome the energy and environmental crises. Bi-based materials present good application prospects, but the development of a new class of electrocatalysts with high performance remains a challenge. Herein, a novel topological chemical transition strategy is developed to rationally design highly active Bi-based materials, which are a new representative of Bi-based electrocatalysts for ERCO2. Bismuth oxysulfate (Bi2O2SO4) is prepared by a simple topological transition from the Bi2S3 precursor in air, which can further topologically transform into the metal Bi by a fast reduction treatment of NaBH4 solution. This kind of Bi2O2SO4 exhibits superior catalytic performance for ERCO2. The maximum Faraday efficiency (FE) of HCOO− is up to 97% at −0.9 V vs. RHE in an H-type cell. A high FE > 90% in a wide potential range of −0.5 to −1.2 V and a large current density of 319 mA cm−2 at −0.8 V can further be realized in a flow cell. The post-characterization studies and density functional theory (DFT) calculations confirm that the Bi2O2SO4 derived Bi catalyst has an optimal (104) plane to realize the optimized free energies of OCHO* and H* reaction intermediates, leading to superior catalytic activity over the NaBH4 derived Bi sample. Our work put forward a promising strategy to exploit advanced electrocatalysts for electrolysis. [ABSTRACT FROM AUTHOR]

Developing high-performance and low-cost self-supporting electrodes as pH-universal electrocatalysts for the hydrogen-evolution reaction (HER) and realizing high-quality hydrogen production at a high current density are highly desirable, but are hugely challenging. We created a self-supporting electrode with a coupled hierarchical heterostructure by simple electrodeposition followed by sulfurization. It comprised oxygen-deficient molybdenum oxide (MoO3−x) and cobalt phosphide (CoP) on nickel foam (NF), which represented a highly active pH-universal electrocatalyst for the HER at a high current density. Benefiting from a plethora of catalytic active sites, improved interfacial charge transfer, and strong electronic interaction, this type of MoO3−x@CoP/NF electrode delivered a superior catalytic performance. Overpotentials of only 100 mV, 135 mV, and 400 mV were needed to realize a high current density of 1 A cm−2 in alkaline, acid and neutral media, respectively, which were superior to those of most other well-developed materials based on non-noble metals. Our experimental work demonstrates the synergistic advantages of a MoO3−x@CoP heterostructure for improving the intrinsic catalytic performance but also paves a new path for the rational design of advanced electrodes for hydrogen generation in a wide range of pH conditions. [ABSTRACT FROM AUTHOR]

Exploiting highly active and low‐cost materials as pH‐universal electrocatalysts for the hydrogen evolution reaction (HER) and achieving high‐purity hydrogen fuel is highly desirable but remains challenging. Herein, a novel type of coupled heterostructure was designed by simple electrodeposition followed by a sulfurization treatment. This hierarchical structure was composed of nickel sulfides (NiS, NiS2, denoted as NiSx) and oxygen‐deficient tungsten oxide (WO2.9), which was directly grown on nickel foam (NF) as self‐supporting electrodes (NiSx‐WO2.9/NF) for HER over a wide pH range. The systematic experimental characterizations confirmed that the material had abundant catalytic active sites, fast interfacial electron transfer ability, and strong electronic interaction, resulting in the optimized reaction kinetics for HER. Consequently, the NiSx‐WO2.9/NF catalyst required low overpotentials of 96 and 117 mV to reach current densities of 50 and 100 mA cm−2 in an alkaline medium, outperforming most of the reported non‐noble metal‐based materials. Moreover, this self‐supported electrode exhibited impressive performance over a wide pH range, only requiring 220 and 304 mV overpotential at 100 mA cm−2 in 0.5 m H2SO4 and 1 m phosphate‐buffered saline electrolytes. This work may offer a new approach to the development of advanced pH‐universal electrodes for hydrogen production. [ABSTRACT FROM AUTHOR]